The Argentine navy raised the possibility on Thursday that a navy submarine missing in the South Atlantic suffered an explosion, heightening concerns over the fate of the 44 crew members on the eighth day of an international search effort.

A sound detected underwater by an international agency on the morning of Nov. 15, around the time the ARA San Juan sent its last signal and in the same area, was “consistent with an explosion,” navy spokesman Enrique Balbi told reporters.

The sub had only a seven-day supply of oxygen, a fact that drained hope from some of the relatives of the crew who have gathered at the vessel’s base in the city of Mar del Plata.

“What’s the point of hope if it’s already over?” Itati Leguizamon, wife of one of the missing crew members, told reporters.

The navy did not have enough information to say what the cause of the explosion could have been or whether the vessel might have been attacked, Balbi said. Source.