Four of the remaining five crew members of the Sincerity Ace were found by the merchant vessels, but they were still in the water and were unresponsive, the Coast Guard said. One crew member remained missing, the agency said.
"If the person in the water can't grab onto something, there's not much these ... vessels can do for them," said Coast Guard spokesman Petty Officer 3rd Class Matthew West. The lowest deck on some of the massive vessels is 25 feet (7.6 meters) to the water, he explained.
The four were not in life rafts.
The Sincerity Ace caught fire early Monday morning about 1,800 nautical miles (2,070 miles) northwest of Hawaii. The Coast Guard has not said what caused the fire on the 650-foot ship.
The Sincerity Ace is adrift on the high seas, the Coast Guard said. Commercial tugs have been dispatched by the company to salvage the ship, the agency said. Company spokesman Darrell Wilson said the vessel was still on fire.
"We are thankful for the assistance the crews of these merchant vessels have given us during this event, significantly reducing possible response time," said Lt. Duane Zitta of the Coast Guard Joint Rescue Coordination Center Honolulu. "Their quick actions provided for the rescue of 16 members of the crew who would otherwise still be in the water, and are continuing to aid us."
Coast Guard and U.S. Navy aircraft are searching a 6,711-mile (10,800-kilometer) area for the missing crewmember, but they don't have any ability to land, West said. The nearest Coast Guard ships are days away, he said. It's not clear what plans are in place to retrieve the four who were unresponsive.
There was no word on what cars, if any, the vessel might be carrying. It has cargo capacity of 21,000 tons and was constructed in 2008.