A committee in the Texas House of Representatives voted 8-5 to advance legislation to increase the minimum age to purchase semi-automatic rifles to 21.
Two Republicans joined Democrats on the committee to pass the bill.
There would be certain exceptions for members of law enforcement and the military.
The passage comes just a day after a man in Texas used an AR-15-style rifle to kill eight people and wound seven others at a mall outside Dallas.
"We can't keep waiting for another tragedy for legislation on gun safety. Nothing can bring back the lives we've lost, but this will help to save lives in the future. We need to see this bill passed," said state Senator Roland Gutierrez.
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Texas is the latest state to propose tighter age restrictions for certain guns.
In April, Colorado raised the minimum age to buy most firearms to 21. Legislation under consideration in Oregon would raise the minimum age to buy a semi-automatic weapon to 21. A California bill would set a minimum age to hold a concealed carry license at 21.
And last year New York passed a law requiring a license to purchase a semi-automatic rifle, effectively raising the minimum age to 21.
The Texas bill now goes to the full House for consideration.
The legislature has three weeks before its session ends on May 29.
