Ann Arbor police continue to investigate two indecent exposure incidents during a roughly two-hour span Tuesday night, but it's unclear whether the cases are related.

At 10:30 p.m. Tuesday, a man parked a station wagon in front of a Frederick Drive home on the city's northeast side, took off his shirt and pants and began to masturbate, police said.

At 12:45 a.m. Wednesday, a man parked a van in front of a Dundee Drive home on the city's southwest side, took off his shirt and pants and began to masturbate, police said.

In each case, the man made eye contact with a teenage girl inside the house while an interior light was on in his car, police said.

According to police, the man in the station wagon was described as white, slightly overweight, with a receding hairline and possibly red hair. The car was dark blue or dark green, police said.

The man in the van was described as white, in his 40s, with thinning hair. The older model van was tan or light in color with a black stripe running down the side, police said.

Police are also investigating whether the incidents are related to a string of similar cases earlier this year in Dexter and Scio Township. So far, no arrests have been made.

Anyone with information can call the department's tip line at (734) 794-6939.