Seven people were injured at around 10:15 this morning after a cable car hit an obstruction and stopped abruptly on Nob Hill. Five people riding the cable car have been hospitalized, one with life-threatening injuries, after the cable car hit an obstacle on Powell and Washington Streets. The conductor and the gripman were both among the injured.

Muni is investigating the accident, which appears to have been caused by a 1.5 inch bolt in the track.