According to official reports, 30 people were injured in the explosion. / AFP PHOTO / STR /
Mayor Enrique Penalosa had said on Twitter that a police officer was killed in the blast, but officials later said that report was a mistake and there were no deaths.
The city hall said 31 people were injured, two of them seriously.
Police cordoned off the area at the center of the blast, where fragments of rubble lay as police explosives experts inspected the site.
The explosion struck near the Plaza Santamaria bullring in the Macarena district.
The bullring was beset by protesters when bullfights resumed there on January 22 after a four-year hiatus.
Those injured on Sunday were mainly police guarding the venue, as they have during every bullfight Sunday since the protests, local media reported.
Penalosa, who overflew the scene in a helicopter, said the area had been secured.
“Anyone who wants to go to the bullfight can do so in safety,” he tweeted.
“The terrorists are not going to intimidate us and we are going to do what is necessary to capture them,” he added.
The authorities have not said who was behind the explosion or whether anti-bullfight activists were suspected.
Closed in 2012 by the city’s former leftist mayor Gustavo Petro, the bullring was ordered to reopen by Colombia’s Constitutional Court.
Colombia’s President Juan Manuel Santos condemned the attack, in a message on Twitter.
“Investigations must go ahead to capture those responsible,” he wrote, expressing his “support for all the wounded police.”
The mayor’s office said it would give more details of the attack later after an emergency security meeting on Sunday afternoon.
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© Agence France-Presse