ISLAMABAD -- At least 31 people were killed and around 170 others were injured after an explosion ripped through a mosque during Friday prayers in Pakistan's federal capital city of Islamabad, police and government officials said.

Confirming the casualties, Deputy Commissioner Islamabad Irfan Nawaz Memon said that the explosion happened in the Shi'ite mosque located in the Shehzad Town area of Islamabad, prompting authorities to impose a state of emergency in all the major hospitals nearby.

He said that the injured are being treated in various hospitals in Islamabad and adjoining Rawalpindi city, adding that the death toll might further rise as several people among the injured are in critical condition.

Following the blast, security forces, police and rescue teams have cordoned off the site and launched a search operation, with the law enforcers investigating the nature of the explosion.

According to eyewitnesses, a suicide bomber detonated himself after being stopped at the entrance of the mosque, causing casualties while damaging the mosque and nearby buildings.

Security measures across the capital remain heightened after the incident.

No individual or group has immediately claimed the attack, but militants such as the Pakistani Taliban and the Islamic State are often involved in attacks against civilians and security forces in the country.

Condemning the blast, Pakistani Prime Minister Shehbaz Sharif expressed deep sorrow and grief over the loss of innocent lives in the blast and extended his sympathies to the bereaved families.