UNION CITY -- Police are seeking a man who broke into a woman's apartment Monday night and held her at knifepoint.

The suspect entered the 35-year-old victim's home on the 1500 block of Decoto Road about 10 p.m. through an open window. When the resident confronted him, the man grabbed her and placed a knife to her throat, Cmdr. Ben Horner said.

He then took her to a bathroom in the apartment and told her to not scream, Horner said. It was not immediately clear what transpired after that.

Police have not said what the man took from the apartment but did confirm a robbery took place.

Witnesses standing outside in the parking lot of the apartment complex told police the man may have fled the scene in a dark-colored, four-door vehicle.

Police described the suspect as a black man, about 40 years old with a medium build. He was wearing a gray or blue sweatshirt and jeans.

Anyone with information is asked to call police at 510-675-5247. Those wishing to remain anonymous can call the tip line at 510-675-5207 or email the tip to tips@unioncity.org.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.