An explosion has rocked a military base west of Iran's capital, Tehran, the BBC reported.

Windows in nearby buildings have been shattered, and the blast was heard in central Tehran, which is 40 kilometers (25 miles) away, according to the news agency.

Ambulances and a helicopter have reportedly been sent to the scene, the BBC noted.

It is unclear what caused the explosion at the base in the village of Bidganeh, near the city of Karaj, the news agency stated.