The blaze, which started Tuesday, began in a section of the building occupied by a picture frame manufacturer and a medical products OEM. The fire then spread to factories within the same structure run by Corrmex, a cardboard box maker, and Foxconn.
The plants employ a reported 1,000 workers. There were no injuries.
The Foxconn plant builds PCs, reportedly for Dell and H-P.
City spokesman Jorge Chairez said Foxconn employees would be sent to work at the company's San Jeronimo facility. The San Jeronimo was recently erected and the company is still moving lines and workers into the factory. The building lacked a sprinkler system, which is typical of older facilities there. City officials are investigating the blaze.