One U.S. soldier died and seven others were injured from an explosion during training at Fort Bragg, N.C., on Thursday, the U.S. Army said.

Staff Sgt. Alexander P. Dalida, 32, of Dunstable, Mass., was killed during Special Forces engineer training, said Lt. Col. Robert Bockholt, a spokesman for the U.S. Army Special Operations Command, in a statement. The cause of his death is under investigation.

It is unclear what exploded. Special Forces students train with numerous munitions and explosives.

Those caught in the blast were a combination of Special Forces students and instructors training at a demolition range used by the John F. Kennedy Special Warfare Center and School. The injured soldiers were evacuated by air and ground to hospitals in the area. In a phone call, Bockholt said he did not know the status of the seven injured but denied reports that four soldiers had died.

Dalida, he said, was the only soldier killed from the explosion.

The incident comes just a day after 14 Marines and one Navy sailor were injured, some severely, when their armored vehicle caught fire in California and two days after a soldier fell to his death from a helicopter in Fort Hood, Tex.

Dalida was enrolled in the the Special Forces “Q,” or qualification, course, and was in the engineer phase of his training. The months-long course involves extensive language instruction and specialty training for certain jobs, such as medical sergeant, weapons sergeant and engineer sergeant.

“Our primary focus right now is to care for his loved ones. We will honor Staff Sgt. Dalida and help his family in their time of need,” said Col. Michael Kornburger, Commander, 1st Special Warfare Training Group, in the statement.

Dalida joined the Army in 2006 and spent around a decade in aviation units before trying out for Special Forces, according to the statement.