Two tankers were targeted by unidentified attackers near the strategically important Strait of Hormuz on Thursday, one operated by a Japanese company, industry minister Hiroshige Seko said.

All 21 Filipino crew members of the Japan-operated Kokuka Courageous escaped uninjured in life rafts and were rescued by a ship heading to the United Arab Emirates, according to the ship’s operator, Kokuka Sangyo Co.

The 19,349-ton tanker was carrying methanol from Saudi Arabia to Singapore when it was attacked in the Gulf of Oman, near the UAE emirate of Fujairah, according to Kokuka Sangyo.

The U.S. Navy’s 5th Fleet said it received distress signals from the Kokuka Courageous and another tanker chartered by a Taiwanese firm at 6:12 a.m. and 7:00 a.m.

A hole that appeared to have been caused by some kind of artillery shell was found on the ship, the company said, adding that a fire broke out in the ship’s engine room but was extinguished by the crew before they abandoned ship.

RELATED STORIES Coalition vows retaliation after Yemen's Houthis strike Saudi airport

“I don’t know why our ship was attacked,” said Kokuka Sangyo President Yutaka Katada. “I’m angry that the lives and safety (of the crew) were threatened.”

The transport ministry said details of the attack and the extent of damage are not yet known, and the tanker is currently drifting without any crew aboard.

The other ship, the 62,849-ton Front Altair, was chartered by Taiwanese oil refiner CPC Corp. to carry naphtha from the UAE to southern Taiwan, company Vice President Chen Ming-hui said.

“The vessel was engulfed in flames but all crew members are safe,” Chen said.

The incident unfolded during Prime Minister Shinzo Abe’s landmark visit to Iran for talks with the country’s Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani to help ease tensions between Tehran and Washington.

Iranian Foreign Minister Javad Zarif suggested the attacks were somehow motivated by the visit, tweeting that “suspicious doesn’t begin to describe what likely transpired this morning” as Abe and Khamenei met “for extensive and friendly talks,” though it was unclear what he meant.

The attacks near the Strait of Hormuz, a key corridor through which a third of all oil traded by sea passes, caused global oil prices to surge. West Texas Intermediate jumped 3.5 percent to $53 a barrel at one point, while Brent crude soared 4.5 percent to $62 a barrel.