Dixons and Epson were forced to close down their offices, and 3Com confirmed that its building has been "damaged" but did not specify to what extent.
A series of explosions hit the Buncefield depot near Hemel Hempstead at around 6am on Sunday. The blast resulted in 43 injuries and forced 2,000 local residents from their homes.
Police have said that the explosions appear to have been caused by a fuel leak and have ruled out a terrorist attack.
Dixons has moved to an alternative location, and Epson said that its offices are "out of action" and "off limits".
The printer maker insisted that it intends to continue operating from temporary offices. The company's business systems and email are operating as normal.
Network equipment maker 3Com has its EMEA head office in Hemel Hempstead, about a quarter of a mile from the blast site. Back-up systems have been activated and the firm expects the accident to have "minimal impact" on customers.
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