Washington — The Immigration and Customs Enforcement field office where a gunman opened fire on Wednesday was also the target of an alleged bomb threat in August, underscoring a pattern of attacks and threats targeting federal facilities and officials in recent months.

On Wednesday, ICE said in a statement that a gunman began firing "indiscriminately" at the field office and its entryway early in the morning. Three detainees were shot, and one died, according to the Department of Homeland Security, which oversees ICE. (The department initially said two detainees had died before issuing a correction.)

No ICE officials were injured, and the gunman died of a self-inflicted gunshot, according to ICE.

Joe Rothrock, the special agent in charge of the FBI's Dallas office, said the

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