An intermittent safety zone is in effect today, as crews with the U.S. Coast Guard work to salvage the hatch of a ship that was blown off in an explosion Aug. 18.

Officials for the U.S. Coast Guard said on social media that the safety zone would include all waters within a 500-yard radius of the location of the hatch cover in the federal channel.

The Port of Baltimore said the channel is closed from 8 a.m.-5 p.m.

Officials for the Coast Guard, which is leading the investigation into the incident, did not immediately respond to a request for comment.

The 751-foot merchant vessel W-Sapphire was south of Fort Carroll at the time an explosion occurred on board. It was near the former site of the Key Bridge, and remnants from the bridge were visible in videos that showed the explosion.

The W-Sapphire was carrying coal when it departed the Curtis Bay piers, bound for the island nation of Mauritius in the Indian Ocean. Investigators have not cited a cause of the explosion.

There were 23 crew members and two local pilots on board the vessel at the time of the explosion, and no injuries were reported.

The W-Sapphire remains moored north of the Chesapeake Bay Bridge, according to online ship tracking data.