Two rampaging drivers who injured a total of 23 people in nearly identical incidents in France were apparently mentally ill and the attacks are unlikely to be linked to terrorism, government officials have said.

Security measures for police and other authorities have been stepped up after a driver said to be shouting “God is great” slammed into crowds in a French city, injuring at least 11 people and raising national concern as Islamic extremists call for attacks.

A man armed with a knife has attacked a police station and been killed by an officer in a suburb of Tours, a city in central France.