It happened on July 23 at the Waffle House located at 11240 Westheimer Rd. near Wilcrest Drive at around 11:50 p.m.
In newly released surveillance video, the men are seen barging into the restaurant and forcing customers to get on the ground.
"They pointed the firearms at us and they told us 'Get on the ground,'" said a witness who was inside the restaurant. "(The men said) 'We need phones, we need your wallets, we need everything.' What felt like 10 minutes was actually only a two to five minute ordeal before the three men were already gone."
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Police say the robbers took the customers' belongings then forced the manager to open the cash register.
"He came over and he, like, pointed the gun at us and told us to get out from under the table, so we did," said a college student who was also inside the restaurant. "We were all just laying there, and we waited until they left."
The men are seen wearing dark clothing and masks. Anyone with information is urged to contact Houston Police.
"They're all coming from a white pickup truck," said Sgt. Tony Mora with HPD. "So, if you recognize someone that fits that description and has the same kind of vehicle, it's an older model pickup truck, that's something we can use."
Crime Stoppers may pay up to $5,000 for information leading to the charging or arrest of the suspects. Information can be reported by calling 713-222-TIPS (8477) or submitted online at www.crime-stoppers.org.