Here is a good short article on this.
‘How a Texas Gunfighter Cop Stopped the ISIS Attack in Garland, Texas’
https://www.ammoland.com/2021/03/how-a-texas-gunfighter-cop-stopped-the-isis-attack-in-garland-texas/#axzz7WfR75xlg
“As Greg engaged Simpson and Soofi, an undercover FBI agent was traveling with the terrorists in a separate vehicle, approaching the rear entrance where the gunfight happened. The agent and two terrorists had traveled all the way from Arizona, in two vehicles. It was claimed the FBI agent took pictures of the attack, just as it started. It was claimed he participated in intelligence gathering, and in planning the attack, advising the terrorists to wait until the event was ending.
The FBI agent, only identified in the following lawsuit as UCE-1, stopped, then attempted to flee the scene.”
Bkmk