TULSA, Oklahoma - Tulsa Police are investigating a robbery that happened at an apartment complex Thursday night.

Police say it happened at the Hunter Creek Apartments near 15th and Memorial around 10:45 Thursday night.

They say a woman met a man there and while they were sitting in the car talking another man walked up and put a knife up to the man's throat.

Police say he demanded they give him their belongings.

He took the items and ran off, but police say one of the victims went after him and somehow got some the items back..

Police are still looking for the robber.

"We surrounded the area pretty quickly," said Sergeant Larry Edwards, Tulsa Police. "Helicopter was up so there's a chance that he either jumped in a vehicle real quick or he went inside an apartment complex."

If you know anything that could help police find him.. you're asked to call Crime Stoppers at 918-596-COPS.