Wednesday’s fatal shooting at a Dallas ICE field office was at least the fourth instance of violence or a threat at an ICE or Customs and Border Protection facility in Texas this year.

One of those instances involved an August bomb threat at the same Dallas facility where Wednesday’s shooting happened, authorities have said.

One ICE detainee was killed in Wednesday’s shooting and two others were hospitalized in critical condition, the Department of Homeland Security said in an afternoon news release. Earlier, DHS said two ICE detainees were dead while another was seriously injured; the revision by the department was provided without additional explanation.