Two cargo ships were attacked in the strategically vital Strait of Hormuz, authorities said Wednesday, after the U.S. extended the ceasefire and as diplomats seek to bring the U.S. and Iran together for peace talks.

A vessel reported being fired upon about eight nautical miles off the coast of Iran, the United Kingdom Maritime Trade Operations, or UKMTO, center said at 8:38 London time (3:38 a.m. ET), which also warned of “high levels of activity” in the Strait of Hormuz area.

The crew were reported to be safe and accounted for, the UKMTO said, and the vessel did not sustain any damage. It was not immediately clear who shot at the ship.

The incident followed an earlier report of an attack that took place roughly 15 miles northeast of Oman at 5:47 a.m. London time.

The UKMTO said a container ship was approached by an Islamic Revolutionary Guard Corps (IRGC) gunboat. The IRGC ship was said to have fired upon the ship, causing “heavy damage” to the bridge. All crew were reported safe.