The incident occurred as centre-left presidential candidate Jorge Alvarez Maynez was delivering a speech in the city of San Pedro Garza Garcia, near Monterrey.

Mr Maynez was uninjured in the collapse, and was seen speaking to supporters following the incident. Several members of his team had been hurt, he said.
The collapse was caused by a sudden gust of wind, Mr Maynez said in a post on X.
Footage has emerged apparently showing the moment the lighting structure collapsed as a number of people were on the stage.
Video posted on social media showed Mr Maynez waving to his supporters and then running for safety as part of the structure toppled over.
State Governor Samuel Garcia urged local residents to stay indoors because of thunderstorms and strong winds in the area.
"If you can, avoid going out because there are storms and atypical winds. I will keep you informed," he wrote on X.
Reacting to the news of the incident, Mexican President Andrés Manuel López Obrador said he was sending "a hug to family members, friends of the victims and political supporters".
Mr Maynez is the candidate of the Citizens' Movement party and is currently trailing in third place in national polls.
The lead-up to the election, which is due to take place on 2 June, has been among the most deadly in the country's history.
A recent survey by Mexican political consultancy firm Integralia said some 200 public servants, politicians and candidates have been murdered or threatened in the lead up to the poll.

bbc