During afternoon prayers on Monday in the high-security zone of Peshawar, Pakistan's northwestern city, a Taliban suicide bomber detonated himself in a mosque packed with worshippers, killing at least 61 people and wounding more than 150 others, mostly police officers, according to security and health officials.

The explosion occurred inside the mosque in the Police Lines neighbourhood at 1:40 p.m., when attendees, including police, army, and bomb disposal squad members, were offering Zuhr (afternoon) prayers. The bomber in the front row detonated himself, according to officials.

According to Lady Reading Hospital officials, 46 patients have died to date.

There were predominantly police officers among the injured.

A brother of the dead Tehreek-e-Taliban Pakistan (TTP) chief, Umar Khalid Khurasani, said that the suicide assault was retaliation for his brother's death in Afghanistan in August.

The proscribed TTP, often known as the Pakistani Taliban, has committed several suicide assaults against security officers.

Superintendent of Police (Investigation), Peshawar, Shazad Kaukab, whose office is next to the mosque, informed the media that he had just entered the mosque to offer prayers when the explosion occurred. He survived the onslaught.

According to a police spokesman, a part of the mosque has collapsed, and numerous individuals are suspected to be buried beneath it.

The bomber infiltrated the heavily guarded mosque through police lines, where four layers of security were present.

According to the Dawn newspaper, citing CCPO Peshawar Muhammad Ijaz Khan, several soldiers are still trapped under the rubble, and rescuers are attempting to free them.

Khan reported that between 300 and 400 police officers were in the neighbourhood at the time of the explosion. A security breach happened, he told the reporters.

Premier Shehbaz Sharif harshly criticized the attack, stating that the perpetrators "have nothing to do with Islam."

"Terrorists seek to instil fear by targeting those tasked with defending Pakistan," he said, promising that the victims' efforts will not go in vain. The entire country is united against the threat of terrorism. In addition, he stated that a comprehensive strategy will be implemented to combat the deteriorating law and order situation in volatile Khyber Pakhtunkhwa and that the federal government will assist provinces in enhancing their anti-terrorism capacity.

Foreign Minister Bilawal Bhutto Zardari also criticized the attack, stating that "terrorist attacks before local and national elections were significant."

Governor of Khyber Pakhtunkhwa Haji Ghulam Ali criticized the explosion and urged the public to give blood for the injured, stating that it would be a "huge favour to the police."

The injured are being transported to Lady Reading Hospital, according to officials.

According to hospital officials, thirteen of the injured were in critical condition.

The hospitals of Peshawar have declared an emergency. The hospital has requested blood donations for the victims.

After the explosion in Peshawar, security in other major cities, including Islamabad, increased. At all access and departure ports of the capital city of Islamabad, security has been strengthened, and snipers have been positioned at "important points and buildings."

Azam Khan, the caretaker chief minister, denounced the incident and sympathised with the victims' families.

Former prime minister Imran Khan condemned the terrorist attack on the mosque in the strongest terms.

"My thoughts and prayers are with the victims' families. The Pakistan Tehreek-e-Insaf tweeted, "It is imperative that we improve our intelligence gathering and properly equip our police forces to combat the growing threat of terrorism."

Last year, 63 people were killed in a similar attack inside a Shia mosque in the Kocha Risaldar neighbourhood.

The TTP, formed in 2007 as an umbrella organization for multiple militant groups, called off a truce with the federal government and instructed its fighters to launch terrorist strikes across the country.

The group, which is thought to be affiliated with al-Qaeda, has been implicated in several violent attacks across Pakistan, including an assault on army headquarters in 2009, assaults on military bases, and the bombing of the Marriott Hotel in Islamabad in 2008.

In 2014, the Pakistani Taliban attacked the Army Public School (APS) in Peshawar's northwest, killing at least 150 individuals, including 131 kids. The attack reverberated around the globe and was severely criticized.