Law enforcers recovered several objects from barracks of prisoners including large quantity of weapons, sharp knives, Jihadi literature, mobile phones, scissors, radio and electric wires.
The confiscated literature also contained pictures of different militant leaders. Rangers spokesman said flags of political parties were also found from some inmates.
All the barracks were thoroughly searched with checking of prisoners.
Earlier during a press conference in the day, Colonel Tahir Mehmood told that the Rangers raided a house where members of a militant group were trying to tunnel into the nearby Karachi Central Jail.
Mehmood said they had arrested suspects from a banned militant organisation but did not name it or say how many were detained.
The Karachi jail holds a large number of high-profile Islamist and sectarian militant detainees and has repeatedly come under threat in recent years.
Mehmood said that the 45-metre (150-feet) tunnel had been dug from an underground water tank at the house towards a dry well inside the jail boundary, and was just 10 metres short of its target when the Rangers made their raid.
“Nearly 100 dangerous terrorists were present in the cell near the well where the suspects wanted to enter through the tunnel,” he said.
Authorities had fortified the jail by erecting double boundary walls in view of the threats and jammers were also installed around the jail to prevent any bomb attack.
Breakouts from Pakistan’s ageing, overcrowded prisons are not uncommon. A raid by heavily armed militants on a jail in the northwest last August freed nearly 250 prisoners, while almost 400 fled in a similar incident in another northwestern prison in 2012.