A woman was shot while riding in a vehicle Monday night in the Pilsen neighborhood on the South Side.

The 21-year-old was a passenger when a male inside another vehicle, a tan Buick, fired shots about 11 p.m. in the 1300 block of West 18th Place, according to Chicago Police.

She was struck twice in the back, police said.

There were at least three people inside the Buick when shots were fired. The woman did not appear to be the intended target, police said.

She was taken to Stroger Hospital where she was in serious condition, police said.

Area Central detectives were investigating.