An attack Thursday on an oil tanker managed by an Israeli-owned company killed two members of the crew when the vessel was apparently struck by an explosive drone, the ship’s management company and a U.S. official said.The attac k on the ship, the Liberian-flagged Mercer Street, occurred in the Arabian Sea off the coast of Oman about 10 p.m. local time, according to an alert sent by the British military’s United Kingdom Maritime Trade Operations. It was the deadliest in a string of recent attacks on tankers and other vessels in the region that have been attributed to Iran or Israel at a moment of rising hostilities between the longtime adversaries.

 Zodiac Maritime, the company that manages the Mercer Street, said in a statement Friday that the crew members killed were from Romania and Britain but did not identify them. The company, which is owned by Eyal Ofer, an Israeli billionaire, said that it was “not aware of harm” to other personnel and that there was no cargo aboard the vessel when it was struck.

On Friday afternoon, the company said the Mercer Street was “sailing under the control of her crew and under her own power at 14 knots to a safe location with a US naval escort.”

Attacks on ships over the past two years, involving commandos, limpet mines, drones or missiles, have raised alarm about passage in the waterways of the Middle East. The attacks have also complicated tense negotiations aimed at restoring the nuclear deal Iran signed with the United States and other global powers, an effort that Israel vigorously opposes.

A U.S. defense official briefed on the latest attack said that the Mercer Street appeared to have been struck by a “one-way explosive drone.” The official, who spoke on the condition of anonymity because of the sensitivity of the issue, said that although it was “too early” to identify the party responsible, the incident bore the hallmarks of an Iranian attack.

The latest strike occurred as the nuclear talks, held in Vienna, are at an impasse, with Iran indicating that it will not return to negotiations until after a government headed by President-elect Ebrahim Raisi takes office in August. The talks began in April and are aimed at restoring the pact, from which President Donald Trump withdrew the United States in 2018.