POLICE  have busted a secret underground shooting range buried three floors beneath a suburban house in Granada believed to be the brainchild of a ruthless gang arming violent drug cartels.

The astonishing discovery came as cops raided the unassuming property in southern Spain, only to stumble upon a high-tech bunker where thugs allegedly tested out assault rifles, submachine guns and pistols – all in complete silence from the street above.

Thanks to the bunker’s extreme depth, neighbours were none the wiser. Not a single gunshot was heard, despite what police described as a full-blown ‘illegal shooting range run by a criminal group’  – a first of its kind in Spain.

The gang is suspected of selling firepower to drug traffickers, who used the deadly gear to defend turf or take out rivals. Alongside the cache of weapons, officers seized €60,000 in cash, and arrested three suspects, with more likely to follow.

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Police also found a treasure trove of gear including bulletproof vests and tactical kit, turning the secret range into what looked like a narco-military boot camp.

“This operation has removed weapons from the streets that could have been used to commit extremely serious crimes,” authorities said in a statement, hailing the sting as a major blow to gangland operations.

Spain has long been a gateway to Europe’s booming drug trade, thanks to close ties with Latin America and its proximity to Morocco – a cannabis kingpin in its own right.

But now, with bunkers turning suburban homes into war zones, it seems Spain’s underworld has quite literally gone underground.