A massive explosion at a military arms depot near the Iranian capital Tehran killed 15 servicemen on Saturday and seriously wounded several others, in what officials were treating as an accident.

A representative of the Revolutionary Guards said the blast happened as troops were moving munitions at a base in Bidganeh, near the town of Shahriar.

My dear colleagues in the Revolutionary Guards were moving munitions in one of the arsenals at that base when, due to an incident, an explosion happened, Ramezan Sharif told state TV news channel IRINN.

Some of the casualties are reported to be in a critical condition, he added.

Residents in western suburbs of Tehran, 45 kilometers (27.9 miles) away, told Reuters they had felt the blast, assuming it to be a low-level earthquake. Some media reports said the initial blast was followed by a second explosion.

The explosion happened around noon local time (0930 GMT), and the fire was still raging at the Amir Al-Momenin military base more than four hours later, the semiofficial Fars news agency said. Media were being kept away from the scene, and no television pictures were immediately available.

There were no reports linking the blast to any air strike or other attack. Tension has risen in recent weeks between Iran and its enemies Israel and the United States, which have not ruled out striking facilities they believe are working toward making nuclear weapons, a charge Tehran denies.

On Oct. 12 last year, a similar blast at a Revolutionary Guards munitions store killed and wounded several servicemen in Khoramabad in western Iran. Authorities said that explosion was an accident.

(Additional reporting by Mitra Amiri; Writing by Robin Pomeroy; Editing by Jon Hemming)