Houston Police Executive Assistant Chief James Jones said the deputies were working an extra shift at the bar when they heard a disturbance outside at around 2.15 a.m. on Saturday, reports Xinhua news agency.
"It turns out it may have been a robbery they were intervening in ... probably unknown to them at the time," Jones said.
"They were trying to arrest a suspect or detain a suspect when they were ambushed."
One of the injured was shot in the back and the other was shot in the foot, Constable Mark Herman said at a news conference.
Both underwent surgery.
The suspect is believed to have shot the officers with a rifle, according to a NBC News report.
The shooting remains under investigation, said the report.
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