A Navy destroyer collided with a merchant vessel off the coast of Singapore

A US Navy destroyer was involved in a collision with a merchant vessel off the coast of Singapore on Sunday, the Navy said.

The destroyer, the USS John S. McCain, collided with the vessel Alnic MC at 6:24 a.m. local time, according to a Navy statement.

The collision occurred east of Singapore and the Strait of Malacca as the destroyer was heading to Singapore for a routine port visit.

There were no immediate reports of injuries, although the Navy said a search-and-rescue operation was underway.

The warship "sustained damage to her port side aft," or the back-left portion of the ship, according to the Navy statement.

The merchant vessel is identified by MarineTraffic.com as a tanker sailing under the Liberian flag.

US Sen. John McCain, whose father and grandfather are the ship's namesake, offered his condolences in a tweet Sunday evening.

"Cindy & I are keeping America's sailors aboard the USS John S McCain in our prayers tonight - appreciate the work of search & rescue crews," McCain said.

The collision is the second such incident in two months, coming after the USS Fitzgerald collided with a merchant vessel southwest of Japan in mid-June.

McCain had recently visited the warship in Vietnam, according to Fox News, which added that earlier this month, the ship sailed past contested man-made islands in the South China Sea.