Videos shot during the bullfight show a section of the multi-storey grandstands collapsing as people scream.
“We have activated the hospital network in Tolima,” Tolima Governor José Ricardo Orozco told local Blu Radio. “At the moment, four people have died: two women, a man and a minor.”
Mayor Juan Carlos Tamayo said 800 spectators were in the sections that collapsed.
Tolima’s health secretary Martha Palacios said at a news conference late Sunday that 322 people had gone to local public and private hospitals to seek treatment after the collapse. Palacio said the deceased minor was an 18-month-old baby.
In addition to the four dead, four more people were in intensive care and two others recovering from surgery.
Orozco said he had requested earlier Sunday that the traditional “corralejas” be suspended in Tolima, but it was kept anyway.
President-elect Gustavo Petro urged local officials to ban such events, noting that it was not the first time an incident like this has occurred.
“I am asking mayors to stop allowing more events that involve killing people or animals,” he said.
Current President Iván Duque announced an investigation into the disaster on Twitter.
“We regret the terrible tragedy recorded in El Espinal, Tolima, during the festivals of San Pedro and San Juan, with the collapse of the stands during a corraleja. We’re going to launch an investigation.”