The Sindh government on Friday beefed up security of the National Bank Cricket Arena where Pakistan Super League (PSL) teams Lahore Qalandars and Quetta Gladiators were conducting their practice sessions, Aaj News reported.

Training sessions of both teams have been postponed, however, the decision of their return to hotels would be taken after reviewing the security situation.

The development comes following a terrorist attack on a police office at Karachi's Shahrah-e-Faisal,the latest attack on security forces as terror incidents see an uptick across the country.

As per reports, a loud explosion was heard after gunmen attacked the Karachi Police office.

Staff inside the premises of the police office had earlier turned off the lights and blocked all entrances. However, reports then said the armed suspects managed to enter the building.

Three floors of the five-storey building have been cleared, said Sindh Chief Minister Murad Ali Shah. He added that two floors and the rooftop remained, stressing that it was early to confirm casualties.

Multiple explosions and continuous firing is also being heard after police sealed off traffic on the main road through the city. Initial reports indicated the attack took place a little after 7pm.