Seven people were killed in an accident at a Grupo Modelo SAB de CV (PINK:GPMCF) brewery in Mexico City Sunday.

Workers were carrying out routine cleaning of a tank at the brewery, when unidentified toxins contaminated the container, according to the Spanish-language newspaper Milenio. The families of the deceased have already been contacted by Grupo Modelo and local authorities.

Grupo Modelo is investigating the cause of the accident to identify the offending toxin or toxins. There is no more danger to other workers at the brewery or residents in the surrounding neighborhood, a company representative told Bloomberg via email.

Grupo Modelo, Mexico’s largest brewer whose Corona brand is also popular in the U.S., is the process of selling itself to Anheuser-Busch InBev NV (NYSE:BUD), the Leuven, Belgium-based parent of the Budweiser unit in the U.S.

The U.S. Justice Department filed a lawsuit in January over concerns the deal would lead to higher beer prices in the U.S., but Grupo Modelo and Anheuser-Busch InBev said Friday they had reached agreement on a framework to settle the suit, according to Reuters.