A submarine has vanished launching a frantic search for 44 people on board

The Argentine Navy began a search on Nov. 17 for the submarine San Juan after contact with it was lost two days previously. Forty-four sailors were aboard. (Argentine Navy)

Argentine authorities are scrambling to find a three-decade-old submarine that suddenly stopped communicating during a routine mission on Wednesday — an emergency authorities say could range from a fried electrical system to something much worse.

The diesel-electric ARA San Juan was returning to its base south of Buenos Aires after a routine mission to Ushuaia, near the southern tip of South America. Then, suddenly, it went silent.

According to the Associated Press, no one has been able to contact the sub or any of its 44 crew members since Wednesday, even though an international collection of rescuers are scanning all radio frequencies and scouring the waters near the San Juan’s most recent ping.

Complicating matters: strong winds and high waves that were battering search-and-rescue ships.

The Argentine government had received logistical help from the governments of Britain, Chile and the United States, including NASA — other countries have also offered aid — but as of Saturday morning, no surface or visual contact had been made, the AP reported.

The sub has multiple ways of communicating. It has ample food and oxygen, the Argentine navy said, and its protocol is to surface if there’s a communications blackout.

“The last position [registered] was two days ago,” navy spokesman Enrique Balbi said, according to the AP. “Without wanting to be alarmist or overdramatic, the facts are that no form of communications could be established between the vessel and its command, even with the alternative methods that the submarine has.

“What we interpret is that there must have been a serious problem with the communications [infrastructure] or with the electrical supply, cables, antennae or other equipment.”

Worried relatives had gathered at the submarine’s base, where they hoped to hear the first updates.