Interior Minister Chaudhry Nisar Ali Khan also expressed deep grief and sorrow over the tragic incident. Armed assailants riding a motorbike launched the assault on law enforcers. Lahore police chief Capt. (R) Amin Wains said that the primary target were police officials.
The prime minister, Nawaz Sharif, condemned the attack in Lahore in a statement issued by his office and urged that the injured be given "the best possible medical treatment".
Gas cylinder blasts are also common in Pakistan, where gas is used for everything from cooking to powering cars.
Punjab government spokesperson Malik Mohammad Ahmed said 26 people lost their lives and 58 were injured when a vehicle bomb struck the old vegetable market.
According to media reports, an operation against encroachments was underway in the area when blast happened.
Police and rescue officials cover a body after a blast in Quetta, Pakistan June 23, 2017.
The old Sabzi Mandi is also situated in the area.
"The condition of several injures is stated to be critical", the official said.
Blood-soaked caps, shoes, pieces of clothes and human flesh lay strewn across the blast site, as paramilitary rangers were called in to join the rescue effort. An emergency has been declared in all nearby hospitals. Forensics teams have started collecting evidence from the blast site, after which the nature of explosion will be confirmed.
Most of the casualties were police officers and some bystanders, he said.
A Police Department spokesperson confirmed that nine policemen were killed in the blast while the injured included at least six policemen.
Lahore has been hit by significant militant attacks in country's more than decade-long war on extremism, but they have been less frequent in recent years.