The crew of the tugboat hauling the last unflown space shuttle external fuel tank to California reports they have rescued four passengers from a fishing boat that sunk off the coast of Mexico.

The tugboat Shannon Dann is currently hauling the fuel tank, known as ET-94, aboard the barge Gulfmaster I. ET-94 left NASA's Michoud Assembly Facility on April 12 and traversed the Panama Canal on April 25 and 26. It will make a final stop in San Diego before arriving in Los Angeles on May 18. The tank will ultimately be joined to space shuttle Endeavour and a pair of solid rocket boosters at the California Science Center, creating a fully stacked space shuttle flight unit.

Officials at the science center say a fishing vessel named Maximus sank off the coast of Mexico on the evening of May 12. ET-94 was roughly 200 miles south of San Diego when it encountered a lifeboat carrying all four Maximus passengers. The crew of the Shannon Dann brought the survivors aboard, and remain en route to San Diego.

"We don't have real communications with the Shannon Dann; we just get text messages twice per day," said Dennis Jenkins, a former NASA veteran now overseeing the project. "They'll berth in San Diego about 8:00 Sunday morning, and we'll find out a whole lot more," he said.

Three of the four passengers from the Maximus were reported to be Americans; the fourth was a Mexican national.