Acting ICE Director Todd Lyons confirmed the shooting during an interview on CNN on Wednesday.

“It could be employees, it could be civilians that were visiting the facility, it could be detainees,” Lyons said of those who were shot.

“At this point, we’re still working through that.”

Two people were taken to a hospital with gunshot wounds, and a third person died at the scene after the shooting, Dallas police spokesperson Officer Jonathan E Maner said in an email.

Parkland Hospital has received two patients from the incident at the ICE facility, hospital spokesperson April Foran said by telephone. She did not have any details about their conditions.

Officers responded to a call to assist an officer on North Stemmons Freeway around 6.40am on Wednesday (9.41pm AEST) and the preliminary investigation determined that a person opened fire at a government building from an adjacent building, Maner said. The investigation is ongoing and a briefing was expected later in the day.

Homeland Security Secretary Kristi Noem said details were still emerging, but the agency was confirming there were “multiple injuries and fatalities” at the field office.

Noem said the motive remained unclear, but noted there has been an uptick in targeting of ICE agents.

Dozens of emergency vehicles were seen along a highway near the facility.

The ICE facility is along Interstate 35 East, just south-west of Dallas Love Field, a large commercial airport serving the Dallas-Fort Worth metropolitan area, and just blocks from hotels catering to airport travellers.

Traffic cameras near the scene showed six lanes of a normally busy freeway empty, with cars and semitrailers ground to a halt on an interstate exit.

ICE and Homeland Security didn’t immediately provide additional details.

The Dallas Fire-Rescue Department was dispatched at 6.41am after a call reporting a shooting at or near the immigration office, department spokesperson Jason L Evans said in an email.

Evans said he didn’t have any confirmed details he could share, calling it an active and ongoing incident.

A July 4 attack at a Texas immigration detention centre injured a police officer, who was shot in the neck.

Attackers dressed in black military-style clothing opened fire outside the Prairieland Detention Centre in Alvarado, south-west of Dallas, federal prosecutors said. At least 11 people have been charged in connection with the attack.

A man with an assault rifle fired dozens of rounds at federal agents as they were leaving a US Border Patrol facility in McAllen on July 7.

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