A cargo ship near the site of the Key Bridge sent out a mayday call after an explosion on board, though no injuries were reported, a Baltimore City Fire Department spokesperson said Monday evening.

A video captured of the incident and shared on social media appears to show a large fireball coming from the front of the coal ship before a large plume of dark smoke floats into the air.

Fire spokesperson John Marsh said the department responded to a call of an explosion aboard the ship, the W-Sapphire, around 6:30 p.m. Responding officials found the 751-foot coal ship “showing signs of damage consistent with a fire and explosion,” Marsh said in a statement.

Marsh said all 23 crew members were safe and that the U.S. Coast Guard would lead the investigation of the incident.

In an emailed statement, a spokesperson for the U.S. Coast Guard said it and other agencies were responding to the reported explosion. The cause of the explosion remains under investigation, the statement said.

The ship has been cleared of the shipping channel, Marsh said. It will be “moved to a designated anchorage area and held there until cleared by the Coast Guard,” he said.

The W-Sapphire departed from the Curtis Bay piers around 5:45 p.m. Monday bound for Mauritius, a small Island east of Madagascar in the Indian Ocean, according to ship tracking data.

It reached a speed of about six knots near the Key Bridge site and then continued sailing, assisted by tugboats. Two hours after the explosion, four tugboats escorted the ship as it sailed past Gibson Island, data showed.

The Maryland Department of Emergency Management said just before 8 p.m. that it was monitoring the situation but that no injuries had been reported.

There was no property damage reported beyond the fire on the ship, it said.

Officials with the Maryland Port Administration and the Maryland Transportation Authority referred questions about the incident to the U.S. Coast Guard.

The Banner’s Matti Gellman contributed to this article. This is a developing story.