TULSA, Oklahoma - Tulsa police are seeing an increase in a particular type of car crash, and it's happening because people are trying to be nice and help others. Police say it sounds strange, but in this case, they're asking you to be a little less helpful.

It's happening so often, Tulsa police even have a name for it. They call them Good Samaritan crashes, where somebody wants to turn, and the turning driver can't see if traffic is clear. The Good Samaritan can see it's clear and waves them through. Then - bam, they get hit.

They say it happens a lot at an intersection at 81st and Memorial when people want to turn left out of the parking lot, but traffic gets backed up at the light. So someone tries to be nice and waves them through, but things change in the blink of an eye. Suddenly, a lane that was clear, isn't any longer, and there's a crash.

It's been such a problem, QuikTrip put up a sign telling drivers not to turn left here.

"When we arrive at these calls, we tell people, don't wave someone through. Situations change dramatically," said Corporal Brian Collum, Tulsa Police Department.

He says technically, when you wave someone through, you are directing traffic and that's against the law. So it could result in a ticket. The only people who can legally direct traffic are police officers, firefighters and construction workers. He's even seen the waving person's insurance have to pay.

"At one point, the companies of the two cars that collided actually went after her insurance so technically, you could be held liable for directing traffic that causes a collision," Collum said.

One insurance agency tells me the driver, not the one who did the waving, has the greater responsibility to get into the intersection safely. Police says they see a lot of these crashes that involve motorcycles because people can't see them as well and of course, they often get hurt worse. He says the next time someone tries to wave you through, politely say no.

"That's what I do, I wave and say thanks but I can't see that lane so I don't go until I can see both lanes are clear," said Corporal Brian Collum, TPD.

Police understand you are just trying to be nice, but they say the next time you have urge to be nice and wave someone through, resist that urge. You let them see if it's clear and let them decide when to go.