ANKARA, Turkey (AP) — Turkey's state-run agency says an explosion inside a van carrying university students in Istanbul has wounded seven people.

Anadolu Agency said that the blast occurred Wednesday as the vehicle — a shuttle bus operated by a private university — was traveling on a highway on the Asian side of the city.

The cause of the explosion wasn't known but private DHA news agency said that police were investigating the possibility that a makeshift bomb was responsible.

Anadolu said the driver lost control of the van during the blast but managed to stop it near roadside barriers.

There was no information on the conditions of the injured passengers who were rushed to nearby hospitals.