The stage collapsed in San Pedro Garza Garcia, a suburb of Monterrey in the state of Nuevo Leon, during an event attended by the progressive candidate Jorge Alvarez Maynez and other members of the Citizens' Movement party.
The collapse was caused by strong wind, President Andres Manuel Lopez Obrador of Mexico said on social media.
In a video statement, Mayor Miguel Trevino announced the deaths and injuries, adding that all of those injured had been taken to hospitals, The New York Times reported.
The stage, which had been erected on a baseball field, was the site of a campaign event for the Citizens' Movement party's candidate for the city's mayoral election, Lorenia Canavati.
The party said that it had cancelled all of its candidates' scheduled events for Thursday after "hurricane-like winds" knocked down the stage.
Progressive candidate Alvarez Maynez posted on social media, stating that he was "fine" after the collapse and that he had been communicating with the state authorities to determine what had happened.
Canavati said that her team was coordinating with the authorities to support the victims, The New York Times reported.
On Wednesday evening, Mexico's meteorological service said that wind gusts of up to about 43 miles per hour were expected in the country's northeast, adding that tornadoes were possible in Nuevo Leon and nearby states.
Samuel Garcia, the governor of Nuevo Leon, in a video message, said that people should take cover from the storm.
"We're witnessing electric storms. Very strong winds and heavy rain are expected for the next two hours," he said. "There's already been a tragedy."
Moreover, people across Mexico will cast ballots for the presidency and over 20,000 local, state and congressional posts on June 2, reported The New York Times.
Citizens' Movement, a centre-left party founded in 1999, is represented in this year's general election by Alvarez Maynez, who has pitched himself as a third-party alternative to the front-runner, Claudia Sheinbaum of the ruling Morena party's coalition, and the opposition's Xochitl Galvez.
(ANI)
