Article updated at 1 p.m. Eastern time.

Crews combing Lake Erie for a plane carrying six people that disappeared overnight shortly after takeoff from a Cleveland airport along the shore are still hopeful that the occupants could be found alive, a Coast Guard official said Friday.

Authorities have "faint hints" but no strong pulse from an emergency locating transmitter, a beacon that could help find the plane carrying three children and three adults, said Capt. Michael Mullen, the chief of response for the Ninth Coast Guard District. The crews searching for the plane are in search-and-rescue mode, not recovery mode, as they ply waters that are about 50 feet deep, he said.

"We're very hopeful. We will be very hopeful up until the point that we have to turn the search off and we switch over to assisting with recovery," Mullen said.

The Columbus-bound Cessna Citation 525 departed Burke Lakefront Airport late Thursday night with six people aboard and disappeared from radar about 2 miles over the lake. Why remains unclear.

Rescuers from the US and Canada have been deployed in search of the aircraft wich dropped off the radar around 11 p.m., Christopher Yaw, public affairs specialist with the Ninth Coast Guard District in Cleveland, told Cleveland.com.

Searchers had found no sign of any debris or the people aboard the plane as of Friday morning, the agency said. Coast Guard official James Cox in Buffalo, N.Y., also said no emergency beacon had been detected.

A rescue boat was deployed to aid in the search overnight but was forced to return due to rough water. A helicopter from US Coast Guard Air Station Detroit and a Royal Canadian Air Force plane were being used. A ship also was headed from Detroit to help with the search.

The waters in the search area are about 50 feet deep, the Coast Guard said.

The plane was headed to Ohio State University Airport northwest of downtown Columbus. Mr. Cox said the plane is kept at a hangar at the airfield, but the six people aboard the aircraft aren't affiliated with OSU.

The missing plane is registered to John T. Fleming, chief executive officer at Superior Beverage Group in Columbus, The Columbus Dispatch reports. Mr. Fleming's father, John W. Fleming, told the Columbus paper that John T. Fleming’s wife, Suzanne, his two teenage sons, a neighbor and a neighbor’s daughter were also on board the plane.

The senior Mr. Fleming described his son as an "experienced pilot."

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“We’re just in shock,” he said.

This report contains material from Reuters.