Sources tell KHOU 11 the employee is in custody and more details are expected to follow Tuesday afternoon.
In an interview on Monday, Harris County Precinct 4 Constable Mark Herman said he and his deputies were working to arrest the bank employee.
One of the victims withdrew $75,000 in cash from the bank and deputies believe the employee possibly tipped off the suspects.
"Our investigation has taken us in the direction to know that there was someone inside the bank, an employee at the bank, that was possibly involved in this and we'll be getting a warrant for her very shortly, and she will be held accountable also." Herman said on Monday.
Johnson turned himself in to a police agency in downtown Houston on Monday, Herman said.
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Mark Herman, Harris County Constable Precinct 4@Pct4Constable
Suspect Travonn Johnson is in custody ! He is the suspected driver of the Chrysler 300 that ran over the victims in the violent robbery last Friday. More arrests will be coming hopefully today!
2:34 PM - Aug 20, 2018
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Johnson is accused of attacking a couple outside their business with three other suspects Friday morning. He is believed to be the driver in the attack who kicked the couple before running over the woman involved.
The four suspects reportedly followed the woman from the bank and when she arrived at her business, they attacked her and attempted to steal her purse.
A deputy showed up on the scene not long after the attack began and the suspects fled the scene - without the purse or the money inside of it.
The deputy arrested one of the suspects minutes later. He has been identified as 31-year-old Davis Dowell Mitchell.
Authorities are still looking for the remaining two suspects involved.
The bank is located at 12907 Farm to Market 1960 Road W in northwest Houston.
The woman was taken to the hospital in critical condition but she is expected to survive. Her husband was treated for injuries on the scene.
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We will update this story as more information becomes available