Several men have committed a series of robberies at knifepoint on Dallas' Katy Trail, police say.

Police said Thursday that they are investigating four such robberies in recent weeks. The incidents occurred between 8 and 10 p.m. on Oct. 21, 25, 29 and Wednesday, police said.

The victims have reported that two or three men younger than 25 have approached them and taken their phones and other property before running off. One of the victims was wearing headphones at the time of the mugging.

Police said anyone exercising on the Katy Trail should be aware of the surroundings and use extra caution when walking or running at night.