Lahore: A powerful bomb blast rocked Pakistan's eastern city of Lahore on Sunday evening, killing at least 70 people and injuring over a 300, ANI quoted Pakistani media as saying.

"Some 65-70 people have been killed, included women and children, and over 250 were injured," an Edhi spokesperson said.

The deafening explosion took place inside a children's park known as Gulshan-i-Iqbal at Iqbal Town here at around 6:30 pm when it was teeming with families, especially women and children, enjoying the Sunday and Easter holiday.

ARY News said 5-6 kg of explosives may have been used in the explosion, which was heard in a large part of Lahore, capital of Punjab province.

An emergency has been declared at all government hospitals in the city, and a heavy contingent of police has cordoned off the area. Pakistan Army troops have been deployed at the park.

Meanwhile, Pakistani newspaper Dawn quoted Iqbal Town Superintendent of Police Dr Muhammad Iqbal as saying that the explosion was a suicide attack.

Punjab province minister Bilal Yasin had earlier confirmed that at least 51 people died in the blast while nearly 200 were injured.

As per media reports, no terror group has yet claimed the attack.

The park is located in a posh-locality in Lahore, the hometown of Prime Minister Nawaz Sharif. The city is comparatively peaceful in an otherwise violence-wracked Pakistan.

Eyewitnesses said there were scattered body parts in the park, where a large number of families, especially women and children, were present on a Sunday evening. The crowd was "unusually large" because of Easter.

"Still a good number of people are in critical condition," Punjab Emergency Services Rescue 1122 spokesperson Deeba Shahnaz said.

Over 100 injured have been shifted to different hospitals of Lahore, she said. Doctors said the death toll may rise.Most of the injured are women and children, Hussain added.

Pakistan Tehreek-e-Insaaf leader Imran Khan strongly condemned the blast.

"Strongly condemn the terror attack in Lahore in which our innocent citizens including women & children lost their lives," he tweeted.

Strongly condemn the terror attack in Lahore in which our innocent citizens including women & children lost their lives. — Imran Khan (@ImranKhanPTI) March 27, 2016

Awami Muslim League chief and former federal information minister Sheikh Rashid Ahmad slammed Punjab Chief Minister Shahbaz Sharif and asked him where was he and other ministers.

"Donate blood at Jinnah hospital, Sheikh Zaid hospital, Faroq Hospital n Bajwah Hospital Lahore," he urged people.

Visited Jinnah Hospital 2 inquire on the injured and show solidarity to the victims. Urgent blood donations required pic.twitter.com/MfPqRDs2zy — Ejaz Chaudhary (@EjazChaudhary) March 27, 2016

Notably, the first international reaction came from India, where Prime Minister Narendra Modi denounced the deadly blast.

"I strongly condemn it. My condolences to families of the deceased and prayers with the injured," PM Modi tweeted.

Heard about the blast in Lahore. I strongly condemn it. My condolences to families of the deceased & prayers with the injured: PM — PMO India (@PMOIndia) March 27, 2016

Later, PM Modi also called up his Pakistani counterpart Nawaz Sharif and offered his "deep condolences" to the victims of the terror attack in Lahore.

Pakistan, a nuclear-armed nation of 190 million people, is plagued by a Taliban insurgency, criminal gangs and sectarian violence. Punjab is its biggest and wealthiest province.

Today's incident reminds of December 16, 2014, Peshawar school massacre. Seven gunmen affiliated with the Tehrik-i-Taliban (TTP) had conducted a terrorist attack on the Army Public School in the northwestern Pakistani city of Peshawar and killed 141 people, including 132 schoolchildren, ranging between eight and eighteen years of age.