A Highland Park couple robbed in their driveway at first thought their sons were pranking them.
Highland Park police said the couple was robbed at knifepoint after coming home from dinner at the Dallas Country Club on Sunday night.
The 73-year-old woman saw two masked men when she got out of the car. One of them tugged at her purse and told her to give him her purse and jewelry.
Believing one of her sons playing a joke on her, she told him, "Like hell I will."
She also tried reaching for the mask on one of the robbers, according to the police report.
"Her immediate reaction was, what was occurring was really not occurring," Sgt. Lance Koppa said.
The other robber went to the other side of the car and put a knife to her husband's chest. He refused to give up his possessions, also thinking he was the butt of a joke by one of his sons, according to the police report.
"I'll stab you if you don't," the assailant told him.
Police were able to track the victims' cellphone to Dallas apartment complex but were not able to find the phone or any suspects. Investigators are looking for surveillance video from nearby homes.
An email blast alerted area residents about the robbery.
"A red flag goes up, and your mind starts moving and you start thinking, 'Oh dear, this is really close,'" Lenn Prince said. "It made me rethink maybe walking by myself early in the morning."
Highland Park police are trying to figure out what led to the crime.
"We don't know at this point if these suspects were waiting or if they just happen upon our victims," Koppa said. "We just don't know that yet."
The Highland Park Department of Public Safety has also reached out to other law enforcement agencies to compare any similarities in crimes.