Three militants last night stormed a police training college in Quetta, prompting a military operation to clear the premises which also houses hundreds of police cadets.

At least 60 policemen have been confirmed dead and 120 cadets injured in an attack on the Police Training College on Saryab Road. 

Reports said three militants forced their entry into the hostel from the front gate around 9:30pm and held hostage an unknown number of cadets.

Balochistan Home Minister Sarfaraz Bugti told media that the three attackers first attacked the watch tower sentry of the academy and after killing the guard, were able to enter the premises. 

Over 120 injured have been taken to hospitals as the military commandoes and soldiers of Frontier Constabulary battle with the militants to clear the training centre situated at the famous Saryab Road, 20 kilometres to the south of the city.

Security sources say that out of the three militants two had blown up themselves while the third was shot dead.

Almost 250 cadets had been got released by SSG commandos. A police cadet named Zubair was killed, as intermittent exchange of fire was still continuing. Two army helicopters were providing aerial surveillance of the area.

Journalists on the ground reported hearing two loud explosions, with one saying the ground shook when the explosion occurred inside the college. The terrorists were said to be carrying AK-47s and grenades.

Troops deploy outside the Police Training Center after an attack on the center in Quetta (REUTERS)

Soldiers arrive at the training college in Quetta (AFP)

It was not immediately clear how many cadets were in the building at the time of the attack. Provincial home minister Mir Sarfaraz Ahmed Bugti said it normally housed around 700 but “recently there was a batch which graduated so I can’t say how many there are now”.

An eyewitness speaking to reporters after making a narrow escape said he saw three terrorists directly enter the barracks. “They started firing. We saw them and started screaming. We ran upstairs towards an exit.” He described the terrorists being covered in shawls.

The barracks and hostel blocks are situated deep inside the compound, making it hard to hear any sounds of gunshots from the building.

Emergency had been declared at all the city hospitals. Most of the injured were being treated at Civil Hospital, of which five sustained bullet wounds, according to hospital sources. Some of the wounded were shifted to the Bolan Medical Complex.

The situation was tense in the area and people remained confined to their houses.

Around 4 am in the morning Sarfraz Bugti confirmed that over 20 people have died in the attack, with the number feared to rise. "99% of the operation is complete, and we'll completely clear the area around dawn."

IG FC Major General Sher Afghan said there is evidence that Lashkar-e-Jhangvi (LeJ) affiliated militants were involved in the attack. "LeJ militants were getting instructions from Afghanistan," he said, adding that further details can't be shared as things stand.

Troops - backed by Frontier Corps - are taking part in the security operation (REUTERS)

Medical workers treat an injured policeman at hospital after militants attacked the Balochistan Police College (AFP)

Balochistan Health Minister Rehmat Saleh Baloch told Waqt News that emergency has been declared in all city hospitals. "The Secretary Health is monitoring the situation,” he says.

Prime Minister Nawaz Sharif has severely condemned the 'cowardly attacked and has called the security agencies to ensure swift action in getting the situation under control.

Balochistan Chief Minister called an emergency meeting.

The IG FC claimed that the terrorists maintained communication with their handlers in Afghanista. He told reporters that the three attackers were armed and wore suicide vests adding that the operation which was undertaken with "precision" took 4 hours to complete. 

The Sariab Road, where the police centre is located, is considered to be one of the most sensitive areas of Quetta, the capital of south-western Balochistan province. Militants have been targeting security forces in the area for almost a decade.

The training college has come under attack in the past in 2008 and 2006, with attackers firing rockets into the college playground.

An injured commando lies on a bed at a local hospital in Quetta (AP)

Relatives of police cadets wait for word outside the Police Training Centre (Reuters)

The attack comes a day after militants belonging to the Baloch Liberation Army on a motorcycle shot dead two coast guards and a civilian and wounded a shopkeeper in a remote southwest coastal town in the same province.

In August, a suicide bombing at a Quetta hospital claimed by the Islamic State group and the Jamaat-ul-Ahrar faction of the Pakistani Taliban killed 73 people, including many of the city’s lawyer community who had gone there to mourn the fatal shooting of a colleague.

Pakistan says intelligence agencies of India and Afghanistan are fanning unrest in Balochistan by helping the rebels and sectarian militant outfits.

Balochistan is also a key region for China’s ambitious $46 billion China-Pakistan Economic Corridor infrastructure project linking its western province of Xinjiang to the Arabian Sea via Pakistan.

Security problems have mired CPEC in the past with numerous separatist attacks, but China has said it is confident the Pakistani military is in control.