U.S. Federal Bureau of Investigation agents have raided a Dallas ISP, knocking the company and almost 50 of its clients offline.

The early morning Thursday raid closed down the operations of Core IP Networks, which operated out of two floors of a Telx collocation facility at 2323 Bryan Street in Dallas. The raid had to do with the activities of a former customer, according to Matthew Simpson, Core IP's CEO. "The FBI is investigating a company that has purchased services from Core IP in the past," he wrote in a note posted to a Google Sites page. "This company does not even collocate with us anywhere, much less 2323 Bryan Street Datacenter."

He did not name the company that is allegedly at the center of the FBI investigation.

FBI spokesman Mark White confirmed that agents had executed a search warrant at the 2323 Bryan Street address on Thursday, but declined to comment further on the matter.

"Currently nearly 50 businesses are completely without access to their e-mail and data," Simpson wrote. "Citizen access to Emergency 911 services are being affected, as Core IP's primary client base consists of telephone companies. "

Simpson said that his company was not involved in any kind of illegal activity. He could not be reached immediately for comment.

It is unusual for the FBI to shut down an entire hosting provider because of the activity of a single customer.