Police are searching for the man they say sexually assaulted a teenager at knifepoint in Brooklyn this week.

The 18-year-old was walking in Sunset Park Monday morning when she cut through the Martin Luther Playground to use the restroom.

Police say a man was waiting inside with a knife and attacked her after she walked in.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-8477, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com.