Police are warning residents about a pair of cellphone robberies that happened Wednesday night on the Northwest Side.

In each incident, the robber walked up to a victim from behind, according to an alert from Chicago Police. He snatched a cellphone in one incident, and struck a victim and forcibly took their cellphone in another.

The first happened about 7:30 p.m. in the 7500 block of North Oleander, and the other incident happened about 7:40 p.m. in the 6600 block of West Berwyn, police said.

The robber is described as a white man, between 20 and 25 years old, standing between 5-foot-7 and 5-foot-9 and weighing between 135 and 140 pounds, police said. He was seen wearing a dark hooded sweatshirt and dark pants.

Anyone with information should call Area North detectives at (312) 744-8263.