Washington (CNN) -- A U.S. military supply ship fired at a small boat in the Persian Gulf on Monday after it came too close, killing one person onboard and wounding three, Defense Department officials said.
The USNS Rappahannock, a fuel resupply ship, fired on what two U.S. officials called a "small, white pleasure craft" 10 miles (16 kilometers) from the Dubai port of Jebel Ali.
The casualties were Indian fishermen, according to the United Arab Emirates' news agency WAM.
U.S. officials expressed their condolences and said the incident is under investigation.
The small boat appeared to be headed for that port, the Defense Department officials said, adding that their information was preliminary. The U.S. ship verbally warned the smaller boat when it was 1,200 yards (1,100 meters) away and fired at least one warning shot before the decision was made to fire shots to disable the boat, the officials said.
"In accordance with Navy force protection procedures, the sailors on the USNS Rappahannock ... used a series of nonlethal, preplanned responses to warn the vessel before resorting to lethal force," the Navy said in a statement.
"The U.S. crew repeatedly attempted to warn the vessel's operators to turn away from their deliberate approach. When those efforts failed to deter the approaching vessel, the security team on the Rappahannock fired rounds from a .50-caliber machine gun."
Officials described the course of events as standard procedures when a small boat gets too close to a U.S. Navy ship.
The officials, who would not be identified because of the sensitivity of the situation, also described the small boat as having made a series of maneuvers, but emphasized they were waiting for more details about what exactly happened.
UAE authorities are investigating the incident, WAM quoted Tariq Ahmed Al Haidan, a Foreign Ministry official, as saying. And a UAE source said the Emirates' government would follow up after a review.
Jebel Ali is 22 miles (35 kilometers) southwest of Dubai and 37 miles (60 kilometers) north of Abu Dhabi. With 67 berths and extensive dry-dock facilities, it is the largest man-made port in the world and the largest port in the Gulf region and in the Middle East.