'Bad prank' causes huge terror alert in Nice

French police detained, then released, four dental students on Monday after they sparked a terror alert at a hospital in Nice.

The group were armed with various fake weapons and one was spotted wearing a traditional djellaba – loose woolen robes, often worn by Arabs.

Although they were apparently in an area of the hospital that is off limits to the public, the students were spotted and 40 officers were sent to deal with the situation.

After an intensive hunt, officers apprehended four sheepish-looking individuals leaving the hospital with a bag containing fake guns and the djellaba witnesses had described.

Detectives said it was a bad prank, which went wrong.