A relative of Arslan, a supporter of the Muttahida Quami Movement (MQM) political party who was detained by paramilitary forces during a raid on MQM's headquarters, protests with others along a street in Karachi March 11, 2015.[Photo/Agencies]

ISLAMABAD - Pakistan paramilitary troops raided the headquarters of a powerful political group in the port city of Karachi early Wednesday and recovered arms and arrested some suspects, officials said.

The forces also sealed the headquarters of the Muttahida Qaumi Movement or MQM for a thorough search of the building, spokesman for the forces, Col. Tahir, said.

MQM is mainly representing the ethnic-Urdu speaking people who migrated from India after the creation of Pakistan in 1947. The MQM has a strong presence in Karachi and some urban areas in southern Sindh province.

"The Rangers (paramilitary forces) conducted the raid after information was received that some miscreants who had awarded death penalty by courts were hiding in the building," the spokesman told reporters at the scene.

Firing was reported after the raid and a cameraman of a private television channel was injured during the firing. Express TV reported that the cameraman, Muhammad Mughal, received bullet injuries and was shifted to hospital.

Dozens of MQM activists arrived at their headquarters and chanted slogans against the raid.

MQM leaders criticized the raid and called for a shutter-down strike in Karachi as a protest.

The local private schools association announced all schools will remain closed on Wednesday. Witnesses said shopkeepers pulled their shutters down in some parts where business open before noon. Transport was also thin in parts of Karachi, the commercial hub of Pakistan.

MQM's central leader, Dr Farooq Sattar, said the raid is an " attempt to push the party to the wall."

Col. Tahir denied any political involvement and said that the security forces conduct intelligence-based raids and without any discrimination.

"The security forces have recovered a huge cache of arms and have taken 10 to 12 people into custody for questioning," he said, adding that those will be released if proved innocent.

The seized arms, which were shown to the media, include Kalashnikovs, G-3 guns, ammunitions, pistols and commandos jackets.

The spokesman said that the arms recovered had been stolen from NATO supply convoys that used to cross into Afghanistan from Pakistan.

The building has been sealed and handed over to the police for a complete search.