France has temporarily suspended the use of stun grenades during high-school protests after a 15-year-old student lost his hand during clashes with police in the northern city of Lens.

Interior Minister Laurent Nuñez announced the suspension on Wednesday, saying the measure would remain in place until the circumstances surrounding Monday’s incident were clarified.

The teenager was injured near Auguste Béhal high school, where police had reportedly confronted a large group of students throwing stones and fireworks. Authorities have said the boy picked up a grenade that later exploded, while protesters have alleged that he was struck directly by a device fired by an officer. Investigators have yet to establish what happened.

“There is a police action that raises questions for all of us within the Ministry of the Interior; it's what happened in Lens,” Nuñez said.

The incident has intensified criticism of police tactics during protests that have spread across France over concerns about deteriorating school conditions, teacher shortages and overcrowded classrooms.

More than 500 schools were fully or partially closed on Wednesday, while the Interior Ministry said 488 people were arrested during Tuesday’s demonstrations and 43 security personnel were injured.

Nuñez also confirmed that France’s police watchdog, IGPN, had opened 18 investigations into officers’ conduct during the demonstrations.

The protests have also seen other serious injuries involving teenagers, including a 14-year-old who suffered facial injuries after being hit by a tear-gas grenade.

The government is facing growing pressure to address both the students’ demands and concerns over the policing of the demonstrations.