An explosion at a fertilizer plant outside Waco at US’ Texas killed some 60 to 70 people and injured hundreds others.

An explosion at a fertilizer plant outside Waco at US’ Texas killed some 60 to 70 people and injured hundreds others.

The report could not be immediately verified by AFP, but KWTX television cited West Emergency Management Services Director George Smith as confirming the death toll.

The explosion comes as the United States was on edge as it pieces through deadly explosions that hit the Boston marathon on Monday, followed by letters, apparently poisoned with ricin, sent to President Barack Obama and a US senator.

The explosion at the West Fertilizer plant occurred just before 8:00 pm (0100 GMT), Waco Assistant Fire Chief Don Yeager told AFP by phone.

The cause was not immediately known but he said it was a anhydrous ammonia explosion.

The blast sent flames shooting into the night sky, leaving the factory a smoldering ruin and leveling buildings for blocks in every direction.