Ten American sailors are missing Monday morning after the USS John S. McCain collided with a commercial vessel off the coast of Singapore, a disaster that could be one of the Navy’s worst in several years.

President Donald Trump initially responded to the accident saying to reporters, “That’s too bad.”

Trump’s comments came just hours after the US destroyer collided with the Alnic MC, a 30,000 ton Liberian-flagged oil and chemical tanker.

The damage to the American vessel was immediate — and catastrophic.

Images newly released from @US7thFleet show damage to McCain, ship is riding low in the water aft. pic.twitter.com/INMAoiJ1Gi — David B Larter (@DavidLarter) August 21, 2017

According to a Navy press release, “Significant damage to the hull resulted in flooding to nearby compartments, including crew berthing, machinery, and communications rooms. Damage control efforts by the crew halted further flooding.”

The cause of the crash is still unclear, but the Navy says an investigation is underway.

In addition to the missing sailors, five others were also injured by the crash. Four were airlifted to a hospital in Singapore for non-life-threatening injuries. The fifth did not require further medical attention.

Trump was asked about the crash when he returned to the White House late Sunday night from a 17-day vacation spent mostly at his golf club in Bedminster, New Jersey. To reporters shouting questions about the collision, he responded, “That’s too bad, too bad.”

According to Newsweek, the reporters asked Trump about the incident 30 minutes before the Navy officially announced that the accident left 10 sailors missing, leaving it unclear as to whether or not Trump had been fully briefed on the issue.

He later tweeted a more complete response to the accident.

Thoughts & prayers are w/ our @USNavy sailors aboard the #USSJohnSMcCain where search & rescue efforts are underway. https://t.co/DQU0zTRXNU — Donald J. Trump (@realDonaldTrump) August 21, 2017

Sen. John McCain also tweeted in response to the crash. The vessel is named after his grandfather and father, both navy admirals.

Cindy & I are keeping America's sailors aboard the USS John S McCain in our prayers tonight - appreciate the work of search & rescue crews https://t.co/jzk9giXbfg — John McCain (@SenJohnMcCain) August 21, 2017

This is the second similar incident this summer between a US warship and a commercial vessel. On June 17, the USS Fitzgerald collided with a Philippine container ship, killing seven American sailors.