A mob of teenagers injured at least two people and robbed others during a brief rampage Friday night in Center City, police said. At least five teens were arrested.

About 9:15 p.m., police started receiving 911 calls of a group of 20 to 40 teens assaulting people. At Juniper and Walnut Streets, police found a man bleeding profusely from the head. He was being treated at Thomas Jefferson University Hospital.

A street robbery was reported at 16th and Spruce Streets, police said. An iPhone was taken in that or another robbery. A man was assaulted at 15th and Sansom Streets, police said. Vandalism was reported at 15th and Locust Streets. - Robert Moran