Police divers have returned to Montrose Harbor, looking for a man believed to have fallen into Lake Michigan with a woman who was rescued early this morning.

The woman, in her 20s, was pulled from water in the 500 block of West Montrose Avenue about 2:05 a.m., authorities said. She was unresponsive and taken to Weiss Memorial Hospital in critical condition.

While emergency crews were on the scene, a witness arrived and said a man had been in the water as well, police said.The witness said the man was wearing a white T-shirt, officials said.

Firefighters and police divers, using a thermal imaging camera, searched the water for a second person but did not find anyone.

The search was called off just before 3 a.m., according to the fire department.

Divers returned later in the morning after determining that the witness was credible, according to Police News Affairs Officer Janel Sedevic.

The water has been too rough for divers, but crews were searching the surface, she said.

Sedevic did not know what the two were doing along the shore