A gunman opened fire and took hostages at a supermarket in southwestern France on Friday, in what the prime minister called a “serious situation,” rattling nerves in a country that has been the site of several terrorist attacks in recent years.
An armed man entered a Super U market in Trèbes, about 50 miles southeast of Toulouse, claiming to be acting on behalf of the Islamic State, although his connection to the militant group was unclear.
The Paris prosecutor’s office, which handles terrorism cases nationwide, said that a terrorism investigation had been opened, but it did not elaborate.
“Shots were heard, a man appears to be holed up in a supermarket, probably with hostages,” Prime Minister Édouard Philippe said from the eastern city of Mulhouse. “A police operation is underway.”
“All of the information we have at the moment suggests that this is a terrorist attack,” Mr. Philippe said, but he declined to comment on conflicting French media reports that two people had been seriously wounded or even killed.
France continues to be on high alert after deadly terrorist attacks struck the country in 2015 and 2016, mainly in Parisand Nice. Although there have not been any large attacks since the one in Nice in July 2016, there have been several smaller-scale assaults by lone individuals, and the French authorities regularly announce that new plots have been thwarted.
The Interior Ministry said on Twitter that a police operation was underway in Trèbes, and Gérard Collomb, the interior minister, said he was heading to the scene.
The local prefecture said on Twitter that the area around the Super U in that town had been cordoned off.
Frédéric de Lanouvelle, a spokesman for the Interior Ministry, told the BFM TV news channel that the gunman was still inside the supermarket, but he said he could not confirm reports about any dead or wounded.
Earlier Friday, in the neighboring city of Carcassonne, a group of four plainclothes police officers were followed by an armed man in a car who shot at them, according to Mr. Philippe. One officer was wounded, but his life is not at risk, Mr. Philippe said.
Although Trèbes and Carcassonne are very close to each other, it is unclear if the incidents in the two cities were related.
The police and security officers have been targeted in a string of attacks over the past two years.
Three police officers — Franck Brinsolaro, Clarissa Jean-Philippe and Ahmed Merabet — were killed in attacks on the satirical newspaper Charlie Hebdoand in a Paris suburb in January 2015.
A year later, on the anniversary of the Charlie Hebdo attack, officers fatally shot a man with fake explosives as he tried to attack a police station in northern Paris.
In June 2016, a Paris police captain and his longtime partner were killed in their home as their 3-year-old son watched. The attack, in Magnanville, was claimed by the Islamic State.
In February 2017, a man armed with two large knives and shouting “God is great” lunged at a military patrol near an entrance to the Louvre. He was shot.
A month later, a gunman was shot and killed by a military patrol at Orly Airport, south of Paris, after he attacked a soldier.
And in April, Xavier Jugelé, 37, a Paris police officer who had responded to the attack at the Bataclan concert hall in November 2015, fell victim to terrorism himself. He was in a police vehicle on the heavily guarded Champs-Élysées when a gunman opened fire, killing him and wounding two other officers, along with a bystander.