A gunman took four hostages in a convenience store on the outskirts of the southern French city of Toulouse on Tuesday, police said.

Authorities weren't certain of the hostage-taker's identity or what he is demanding. No injuries have been reported.

The man seized the hostages at 4:20pm (1420 GMT) Tuesday in the town of Blagnac, near Toulouse airport, according to a national police spokeswoman.

Local state television France 3 reported that the hostage-taker fired three shots in the air, is wearing a helmet fitted with a camera and demanded to speak with a negotiator.

Police locked down the neighbourhood, evacuating some buildings and ordering other residents to stay inside, according to neighbour Robert Texier. A police helicopter circled overhead.

The police spokeswoman and a security official said it was too early to rule out terrorism without knowing the hostage-taker's demands. Both officials spoke on condition of anonymity because they weren't authorised to be publicly named. The national terrorism prosecutor's office said it is following the situation.

“It's worrying. It all happened so quickly,” said Texier, who expressed surprise at the incident in what he described as a quiet neighbourhood on the banks of the Garonne River. He said the convenience store has been run for decades by a woman and her daughter who live in the adjacent building.