The attack late on Monday had triggered a stampede-like situation at Saadatganj.
A major tragedy was, however, averted when a group of Shia mourners held the bull by its horns and pushed it aside.
An ambulance was called and the injured mourners shifted to KGMU Trauma Centre. Three with critical injuries were hospitalised while others released after first aid. Those hospitalized included Nadeem Rizvi, 55, Zafar Abbas, 28, and Laraib Zaidi, 25.
People in the area have blamed the district administration for not making adequate arrangements like barricading to check stray animals or secure the route for the iconic procession which marked the 150th year of Lucknow's legacy.
The district administration had swung into action after a video of the incident had gone viral.
The Lucknow Municipal Corporation has formed a committee to probe why stray bulls were not removed from the area.
"Municipal Commissioner has formed a panel headed by Additional Commissioner Amit Singh to fix responsibility on those entrusted with the job," said LMC Chief Veterinary Officer Arvind Rao.
Despite the security breach, District Magistrate Kaushal Raj Sharma passed the buck on corporators. "It's the responsibility of the corporators to curb stray menace. If they cannot do it, they should seek LMC's help," he said.
This was tenth attack by a stray animal in the city in two months.
( With inputs from IANS )