A woman was sexually assaulted Wednesday afternoon in the Albany Park neighborhood on the Northwest Side.

The 26-year-old was entering her building about 1 p.m. in the 3400 block of West Irving Park Road when a man followed her inside, Chicago Police said.

The man knocked her down, showed a knife and sexually assaulted her before running away, police said.

He was described as Hispanic, about 30 years old, 6-foot-1 and 210 pounds with dark hair worn in a bun, police said. He was wearing a black T-shirt, tan cargo shorts and black slip on sandals.

Anyone with information should call Area North detectives at (312) 744-8261.