More than 2,000 high school students in northern France were evacuated Monday while security forces searched school grounds for evidence of a threat made on the internet, local authorities said.
The threat was posted on Twitter by a young man who claimed to have placed radio-controlled bombs in hidden locations, broadcaster France Info reported.
The Oise prefecture said in a statement that the students of Mireille Grenet school, located nearly 100 kilometres north of Paris, had left the school calmly, and that most made their way directly home or were picked up by their parents.
Security forces are scouring the school's 59,000 square metres and an investigation was opened into the tweet's author, the prefecture said.
France has been in a state of emergency for two months since a series of terrorist attacks in Paris on November 13 left 130 people dead.
A man wielding an axe was shot dead outside a Paris police station last week, the latest in a series of incidents that have set the country on edge and prompted a broad debate over security.