A Seattle man and Burien woman are believed to be missing after the boat they were on was found unoccupied in Lake Washington, according to the Mercer Island Police Department.

Mercer Island police were called at about 10:30 p.m. Monday with reports that the boat, offshore of the 7700 block of West Mercer Way, was playing loud music. The red, 20-foot boat, described by police as a “ski-type boat,” was unoccupied, but there was evidence that at least two people had been on it that evening.

After speaking to friends and family of the two people thought to have been on the boat, police believe they are a 30-year-old man from Seattle and a 33-year-old woman from Burien, said police Cmdr. Jeff Magnan. The man was one of the boat’s owners, he said.

The U.S. Coast Guard suspended its search early Wednesday, after the lake was searched with a helicopter and marine units. Mercer Island police located a truck and trailer associated with the boat at Gene Coulon Park in Renton. ¬†Police ¬†are working to get data off the boaters’ cellphones, which were left on the boat, that might help pinpoint where the boat was when they were last on it.

Family and friends of the woman told police that she wasn’t a strong swimmer. Police believe it’s possible the woman fell in the lake and the man went in to help her, Magnan said. There was no evidence of foul play or anyone else being on the boat, he said.

Anyone with information that could help locate the man and woman is urged to call the Coast Guard’s Puget Sound Command Center at 206-217-6001.