Eighteen people were hospitalized for smoke inhalation Monday after a Mexico City Metro station filled up with smoke due to an apparent short circuit.

The incident occurred at the Barranca del Muerto station on Line 7 of the Metro system at about 10:50 a.m.

Mayor Claudia Sheinbaum said on social media that 18 people were assessed for smoke inhalation at the San Ángel Inn Hospital. She said that none were seriously ill and later reported that all 18 had left hospital.

Mexico City Civil Protection authorities reported earlier that a total of 30 people were treated for smoke inhalation but that 12 of that number didn’t require hospitalization.

At a press conference late Monday afternoon, Metro Director Guillermo Calderón announced that the incident had been caused by overheating on the track due to a traction cable being missing. He explained that the 750-volt traction cable system is made up of nine cables, but upon inspection, only eight were found.

Passengers on a train passing through Barranca del Muerto reported hearing an explosion before a thick blanket of smoke filled the station.

Train service was suspended between the Barranca del Muerto and San Pedro de los Pinos stations, but had resumed by mid afternoon. Metro officials said that the incident — which it described as an “atypical event” — was referred to the Mexico City Attorney General’s Office (FGJ) for investigation.

Lía Límón, mayor of the Álvaro Obregón borough in which the Barranca del Muerto station is located, claimed in a video message that the incident was related to a lack of funding for the Metro system.

“The National Guard is useless here,” she said, referring to the recent deployment of over 6,000 troops to provide security in the Metro system.

“What’s needed are resources to provide maintenance to the Metro,” Límón said.

Monday’s incident came two weeks after a fatal accident involving two trains on Line 3 of the Metro system and a week after two adjoining cars of a train became detached from each other at Polanco station on Line 7.

Authorities have suggested that recent “atypical” incidents were the result of sabotage, and Sheinbaum has expressed confidence that the FGJ will hold those responsible accountable for their actions.

A recent poll indicated that the recent fatal Metro crash had a negative impact on the reputation of the mayor, who denies claims that the subway system is underfunded.

But incidents on the capital’s Metro system in the past two years have tarnished the administration of Sheinbaum, who took office in late 2018.

In addition to this month’s accident and incidents, an overpass collapse on Line 12 claimed the lives of 26 passengers in May 2021. A police officer died in a fire in the subway system’s downtown substation in January of the same year.

With reports from El País, El Financiero, Infobae and Reforma