The U.S. Coast Guard spent hours searching the waters off Louisiana for four people on board a helicopter that crashed Thursday while departing an oil platform.

“It is always a difficult decision to suspend a search,” said Lt. Cmdr. Kevin Keefe, Coast Guard Sector New Orleans Search and Rescue Mission Coordinator. It was not immediately clear if the search would resume Friday morning.

The helicopter’s pilot and three oil workers went down in the Gulf of Mexico at about 8:40 a.m. CST, said Petty Officer Jose Hernandez, a spokesperson for the Coast Guard’s 8th District, which is headquartered in New Orleans.

“So far we’ve only found debris and no people,” Hernandez said. Photos of the debris released by the Coast Guard showed a cluster of cylindrical yellow objects bobbing in the water.

One of the missing workers is 36-year-old David Scarborough of Lizana, Mississippi, according to his wife, Lacy Scarborough. She told the Sun Herald newspaper that they are expecting a baby, and that her husband recently got a job promotion.

She said her family was praying that her husband and the others would be rescued safely.

“He enjoyed his job and his coworkers,” she said.

Crews in a boat and a helicopter searched for eight hours, covering and area of roughly 180 square miles (460 square kilometers).

Weather didn’t appear to be a factor in the crash, Hernandez said, as there were no reports of storms in the area Thursday.

The helicopter went down about 10 miles (16 kilometers) offshore from Southwest Pass, a shipping channel at the mouth of the Mississippi River southeast of New Orleans. Helicopters routinely transport workers to and from oil platforms in the Gulf.

Hernandez said the oil platform is operated by Houston-based Walter Oil and Gas. The Associated Press reached out to a spokesperson for the company, who was not immediately available for comment.

The National Transportation Safety Board said it is investigating the crash.

Two weeks ago, the Coast Guard rescued three people after a helicopter crashed off the Louisiana coast while attempting to land on an oil rig platform. That crash occurred Dec. 15 south of Terrebonne Bay, roughly 60 miles (97 kilometers) west of the area the Coast Guard was searching Thursday.