A Texas lawyer was shot and killed outside a McDonald's after trying to calm down an angry customer, police say.

Jeffrey Limmer, 46, died after the incident in Houston on Saturday evening and his attacker fled the scene in a pickup truck. The customer was upset with employees over his order and demanded a refund.

Mr Limmer tried to calm them down, according to local news outlet ABC13. Police say the fight went outside and Mr Limmer pushed the customer to the ground.

The customer then went to his car and pulled out a gun and allegedly shot him before fleeing the scene, detectives say. In an interview with ABC13, Mr Limmer's sister Jennifer Thomas praised her brother.

"He loved fiercely his family and friends," she said. "Always laughing, making jokes, and just loving life." Ms Thomas said her brother spent his career trying to help others, so it came as no surprise to her when she heard that was what he was doing when he died.

Read more from Sky News:Boeing delays first ever astronaut launchGrease star dies "Knowing Jeff, he's the one who always says, 'Calm down. It's not that big of a deal,' and divert the situation," Ms Thomas said.

"He's always wanted to fight for the little guy and do the right thing." Police were still trying to locate the shooter on Tuesday..