Several training grenades were thrown into the courtyard of a mosque in the French city of Le Mans. One of the grenades exploded, but no injuries were reported.

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Four training grenades were thrown onto the property overnight Thursday, the local French daily Ouest-France reports.Three of the unexploded grenades were discovered by police. Police have cordoned off the mosque and so far no arrests have been made.

A gunshot was also reported overnight, with the bullet hitting the mosque.

French police have noted several attacks against mosques since Wednesday, when gunmen opened fire on the Paris office of the French satirical weekly Charlie Hebdo.

On Thursday morning, an explosion was reported in a kebab shop near a mosque in Villefranche-sur-Saone, eastern France. There are no reports of any injuries and the cause of the blast remains unknown.

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The mayor of Villefranche, Perrut Bernard, said he was afraid the blast was linked “to the dramatic event that occurred on Wednesday."

Local authorities have told AFP the incident is being investigated.

An assailant also opened fire near a Muslim prayer room in the Port-la-Nouvelle district near Narbonne in southern France on Wednesday night. The door to the room was damaged and a window was broken, but no injuries were reported in the attack. The local prosecutor told AFP the room was empty at the time of the attack.

An investigation into the incident is currently underway.

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Tensions are running high following the dramatic assault on Wednesday, which left 10 journalists and 2 police officers dead. French authorities have introduced the highest state of alert in the country. According to French Prime Minister Manuel Valls, extra security forces have been deployed to secure mosques, synagogues, department stores, shopping centers, train stations and airports.

The French PM added that an extra 650 soldiers and 2,000 more police officers will patrol the streets of Paris on Thursday.