Seattle rescue crews responded twice to Lake Washington near Seward Park Sunday evening to search for two people who were reported missing in the water, police said.

The search resumed Monday morning, police said, but no further updates were immediately available.

The first call came in around 5:30 p.m. Sunday from north of Andrews Bay, where a group of people were on a boat and decided to go swimming, according to a statement from the Seattle Police Department. Witnesses told police one person — a man in his 20s — had seemed to be in distress, the statement said. Four people tried to help him and bring him back onto the boat, but he “slipped through their grasp and went underwater,” police said.

Divers from the police and fire department responded to the lake, but couldn’t find the man.

Rescue teams returned to the lake around 8:40 p.m. after receiving reports that a female passenger on a ski boat fell overboard, police said. The boat’s driver jumped into the water, but he wasn’t able to find her, the statement said.

Seattle fire crews, police officials and a Coast Guard helicopter arrived to search the area, but after more than an hour, crews had not found the missing person, the fire department said.