Islamabad, May 20 (IANS): Security forces in Pakistan have arrested the mastermind of a May 13 bus attack that killed over 40 minority Ismaili Shiites in the port city of Karachi, a cabinet minister said on Wednesday.

Interior Minister Chaudhary Nisar Ali Khan told reporters that several others involved in the bus attack were also detained. He said those arrested belong to different groups. However, he did not identify the groups, reports Dawn.

"The arrest is a big achievement that the culprits have been nabbed within just four days," Khan said.

The Ismailis came under attack when they were heading to their place of worship. Some 46 people, including 16 women, were killed in the attack and several others were injured.

The Islamic State and the banned Jundullah group had claimed responsibility for the May 13 attack.

Officials say that six terrorists were involved in the attack and they fled the scene on three motorbikes.

Syed Qaim Ali Shah, Chief Minister of Sindh province of which Karachi is the capital, said security officials believed the al-Qaida Indian sub-continent branch was behind the attack.