A fire and explosion were reported on a vessel operated by HMM in the Strait of Hormuz on Monday, according to officials in Seoul.

The government is checking reports that the ship, HMM Namu, may have been attacked, as reported by Yonhap News citing officials.

Authorities said there were no casualties. The fire reportedly started in the engine room of the Panama-flagged cargo ship. An investigation is ongoing to find out the exact cause of the incident.

There were 24 crew members on board, including six Korean nationals, the company told Reuters.

Meanwhile, the United States Navy said two of its guided-missile destroyers entered the Gulf to help break what it described as an Iranian blockade. It also said two U.S. merchant ships had safely passed through the Strait of Hormuz.

“Our government will communicate closely with relevant countries regarding this matter and take necessary measures to ensure the safety of our vessels and crew members inside the Strait of Hormuz,” South Korea’s foreign ministry said in a statement.

Seoul has also said that 26 South Korean-flagged ships are currently stranded in the area.