Prime Minister David Cameron said Britain's emergency response committee will meet Friday in the wake of terror attacks in France and Tunisia.

He expressed his solidarity with the French people over the assault on a gas factory, owned by Allentown-based Air Products & Chemicals Inc, and said he hoped to speak later with the Tunisian government to offer sympathy and condolences over beach hotel shootings in the resort of Sousse that have left at least 27 people dead.

"This is a threat that faces all of us, these events that have taken place today in Tunisia and in France, but they can happen anywhere - we all face this threat," he told reporters.

A decapitated body covered in Arabic writing was found at a U.S. gas company in southeast France on Friday, police sources and French media said, after an assailant rammed a car into the premises, triggering an explosion.

The attacker survived the blast and was arrested. A source close to the investigation said the beheaded victim was the manager of the man suspected of ramming a delivery vehicle into gas canisters at the site.

The source said the two had gone to the company's premises together to make a delivery. But the suspect killed and decapitated his victim before then driving their vehicle into the site, the source said.

Speaking from a European Union summit in Brussels, French President Francois Hollande described it as a terrorist attack and said all measures would be taken to stop any future strikes on a country still reeling from Islamist assaults in January.

Interior Minister Bernard Cazeneuve said one suspect, named as Yassin Sahli, had been arrested, and police were holding other suspected accomplices. He said Sahli did not have a criminal record but had been under surveillance from 2006 to 2008 on suspicion of having become radicalized.

In a statement, Air Products & Chemicals said "Emergency services are on site and have contained the situation. The site is secure. Our crisis and emergency response teams have been activated and are working closely with all relevant authorities."

The site was immediately ringfenced by police and emergency services.

Allentown Mayor Ed Pawlowski Friday said “the thoughts and prayers of the residents of Allentown go out to the victims and their families and the employees of Air Products.  We share in everyone’s hope that all the perpetrators of the attack are brought to justice.

“Air Products has always been a tremendous corporate citizen and friend to the City of Allentown.  We pray that the company’s leaders and employees find comfort in the days ahead.”

The chairman and CEO of Air Products is Seifi Ghasemi, who in 2011 testimony to a U.S. Senate committee described himself as Iranian-born. Mainly Shi'ite Iran is a sworn enemy of Sunni-dominated Islamic State. 

Meanwhile, at least 27 people, including foreign tourists, were killed when at least one gunman opened fire on a Tunisian beachside hotel in the popular resort of Sousse on Friday, an interior ministry spokesman said.

Police were still clearing the area around the Imperial Marhaba hotel and the body of one gunman lay at the scene with a Kalashnikov assault rifle after he was shot in an exchange of gunfire, a security source at the scene said.

Police officers control the crowd (rear) while surrounding a man (front C) suspected to be involved in opening fire on a beachside hotel in Sousse, Tunisia, as a woman reacts.  (Amine Ben Aziza/Reuters)  

It was the second major attack in the North African country this year, and took place during the holy Muslim month of Ramadan.

"One attacker opened fire with a Kalashnikov on tourists and Tunisians on the beach of the hotel," said a hotel worker at the site. "It was just one attacker. He was a young guy dressed in shorts like he was a tourist himself."

Tunisia, which has been hailed as a model of democratic transition since its 2011 'Arab Spring' uprising, is one of the most secular countries in the Arab world. Its beach resorts and nightclubs on the Mediterranean are popular with European visitors.

No one immediately claimed the attack. But Islamist jihadists have attacked North African tourist sites before, seeing them as legitimate targets because of their open Western lifestyles and tolerance of alcohol.

Six other people were wounded, the ministry spokesman said.

Irishwoman Elizabeth O'Brien, who was staying at a neighboring hotel with her two sons, said there was panic on the beach when gunfire erupted.

"I honestly thought it was fireworks and then when I saw people running... I thought, my God, it is shooting," she told Irish radio station RTE. "The waiters and the security on the beach started to say 'Run, run, run!'"

Sousse is one of Tunisia's most popular beach resorts, drawing visitors from Europe and neighboring North African countries. Tourism is also a major source of income for the government.

Tunisia has been on high alert since March, when Islamist militant gunmen attacked the Bardo museum in Tunis, killing a group of foreign tourists in one of the worst attacks in a decade in the North African country.

Since its 2011 uprising to oust autocrat Zine el-Abidine Ben Ali, Tunisia has been praised for its peaceful democratic transition. But it has also seen the rise of hardline conservative Islamist movements.

Several thousand Tunisian jihadists have left to fight in Syria, Iraq and neighboring Libya, where some have set up jihadist training camps and promised to return to attack their homeland.

In the French attack "two individuals deliberately rammed a car into the gas containers to trigger an explosion," a police source said of the attack in an industrial zone by the town of Saint-Quentin Fallavier, 20 miles southeast of Lyon.

However the number of assailants was thrown into doubt, with Hollande saying it could have been either one or two.

French media said the suspect in the factory attack, Sahli, was a 35-year-old professional driver who lived in the Lyon suburbs. There was no official confirmation of that.

"The attack was of a terrorist nature since a body was discovered, decapitated and with inscriptions," Hollande told the news conference.

"We all remember what has happened in our country, and not just in our country. So there is plenty of emotion. But emotion cannot be the only response - that must be action, prevention and dissuasion."

The attack underlined yet again the difficulty for authorities across Europe and elsewhere of protecting so-called "soft" targets against strikes by assailants operating by themselves or in small undercover cells. At least 27 people were killed on Friday in an attack on a hotel in Tunisia.

ISLAMIST FLAG

Police sources earlier said the decapitated body was found at the site, along with a flag bearing Islamist inscriptions.

Local newspaper Le Dauphine said the head covered in Arabic writing was found on a fence.

The French public prosecutor said its anti-terrorist section had been deployed to investigate.

France, which has deployed aircraft to the international coalition fighting Islamic State insurgents in Iraq, has long been named on Islamist sites as a primary target for attacks.

In January, Islamist gunmen killed 17 people in the offices of the Charlie Hebdo satirical weekly and a Jewish food store.

In April, Prime Minister Manuel Valls said no fewer than five attacks had been thwarted in the country since then.

Noting that hundreds of French nationals are in Syria where they risked being radicalized by Islamist fighters, Valls has said repeatedly that France has never seen a higher threat level.

No group has claimed responsibility for the attack and the motive was unknown.

According to French regulations applicable to zones where gases and chemicals are handled, the site would have been required to implement security arrangements at the low end of the European Union's so-called "Seveso" scale, named after the location of an industrial accident in northern Italy in 1976.

Cazeneuve said the government had ordered security to be stepped up around all sensitive sites.

He said the Britain's COBRA emergency committee would meet later on Friday "to make sure we are doing everything we can to co-operate and co-ordinate with other countries ..."

He added: "we have to deal with this poisonous radical narrative that is turning so many young minds and we have to combat it with everything we have."