Argentina's navy announced Thursday that a sound detected during the search for a missing submarine apparently came from an explosion — an ominous development that prompted relatives of the 44 crew members to burst into tears.
Navy spokesman Enrique Balbi said the search will continue until there is full certainty about the fate of the ARA San Juan.
He said evidence showed "an anomalous event that was singular, short, violent and non-nuclear that was consistent with an explosion."
"According to this report, there was an explosion," Balbi told reporters. "We don't know what caused an explosion of these characteristics at this site on this date."
U.S. and specialist agencies said the "hydro-acoustic anomaly" was produced just hours after the navy lost contact with the submarine on Nov. 15.
The sub was originally scheduled to arrive Monday at the Mar del Plata Navy Base, about 250 miles (400 kilometers) southeast of Buenos Aires. Relatives of the crew who have gathered at the base to receive psychological counseling broke into tears and hugged each other after they received the news. Some lashed out in anger at the navy's response.
"They sent a piece of crap to sail," said Itati Leguizamon, wife of submarine crew member German Suarez. "They inaugurated a submarine with a coat of paint and a flag in 2014, but without any equipment inside. The navy is to blame for its 15 years of abandonment."
The German-built diesel-electric TR-1700 class submarine was commissioned in 1985 and was most recently refit in 2014.
During the $12 million retrofitting, the vessel was cut in half and had its engines and batteries replaced. Experts say that refits can be difficult because they involve integrating systems produced by different manufacturers and even the smallest mistake during the cutting phase of the operation can put the safety of the ship and the crew at risk.
The Argentine navy and outside experts have said that even if the ARA San Juan is intact, its crew might have only enough oxygen to be submerged seven to 10 days.
Balbi said Wednesday that Argentine navy ships as well as a U.S. P-8 Poseidon aircraft and a Brazilian air force plane would return to the area to check out the sound, which originated about 30 miles north of the submarine's last registered position.
U.S. Navy Lt. Lily Hinz later said the unusual sound detected underwater could not be attributed to marine life or naturally occurring noise in the ocean.
"It was not a whale, and it is not a regularly occurring sound," Hinz said.
The San Juan went missing as it was sailing from the extreme southern port of Ushuaia to the city of Mar del Plata, about 250 miles (400 kilometers) southeast of Buenos Aires.
More than a dozen airplanes and ships are participating in the multinational search despite stormy weather that has caused waves of more than 20 feet (6 meters). Search teams are combing an area of some 185,000 square miles (480,000 square kilometers), which is roughly the size of Spain.
The U.S. government has sent two P-8 Poseidons, a naval research ship, a submarine rescue chamber and sonar-equipped underwater vehicles. U.S. Navy sailors from the San Diego-based Undersea Rescue Command are also helping with the search.
Britain's Ministry of Defense sent a special airplane with emergency life support pods to join the hunt that includes planes and ships from a dozen nations.