A 17-year-old boy has been remanded in custody by the Children’s Court after being charged with two counts of murder when two pedestrians who were walking their dogs were hit and killed by a car in Alexandra Hills, east of Brisbane.

The teenager is accused of being “adversely affected by an intoxicating substance” when he struck Katherine Leadbetter, who was pregnant, and her partner, Matthew Field, as they crossed an intersection just before 5.30pm on Tuesday.

Police said the boy had stolen a 4WD about an hour before the crash from a home in nearby Cleveland.

He then allegedly deliberately collided with a car at the corner of Vienna and Finucane Roads before speeding away, Assistant Commissioner for the Brisbane region Brian Codd said.

Fifteen minutes later, it is alleged he returned to the same intersection, ran a red light, crashed into an oncoming truck and then rolled onto Ms Leadbetter, 31, and Mr Field, 37.

They died at the scene.

The teenager, from the Logan suburb of Waterford West, then ran from the scene.

Police said he stole a set of keys from a home and was trying to start the car in the garage when the owner approached him.

He fled again but was followed by the owner to Chelsea Crescent, where he was arrested by police.

Assistant Commissioner Codd said it was a catastrophic scene, as witnesses worked on the couple before paramedics arrived.

“Tragically, and from advice from family and the Queensland Ambulance Service, we understand that Katherine was pregnant,” he said.

“At this point, we are awaiting the confirmation of the pregnancy, there is provision under the criminal code relating to the killing of unborn children.

“Here are two people going about their business innocently on Australia Day walking their dogs, they should be entitled to do that, and to have them ripped away from their family is a tragedy.

“Family is devastated by this loss.”

Ms Leadbetter was pregnant when she and Mr Field were struck by the 4WD. Photo: Supplied

A Queensland Ambulance Service spokesperson said 10 crews, including critical care paramedics and a medical director responded to the incident.

Six people were treated by paramedics at the scene for shock and minor injuries.

The teenager was taken to hospital for minor “soft tissue” injuries and spent the night in the watch house.

Police said charges included two counts of murder, dangerous driving (adversely affected by an intoxicating substance) and burglary.

“Unfortunately, I am unable to go into detail about any history or interaction that that juvenile may have had with authorities,” Assistant Commissioner Codd said.

The 17-year-old has been remanded in custody after the matter was briefly heard in Brisbane’s Childrens Court on Wednesday afternoon.

The teen was not able to apply for bail due to the nature of the charges, with the hearing adjourned until March.

Outside court, the teenager’s lawyer Patrick Horgan described the situation as “a very traumatic experience” for everyone involved.

Flowers have been laid at the site in tribute of the couple, who are from Alexandra Hills, and their unborn child.

The vehicle that hit the couple. Photo: ABC

Premier Annastacia Palaszczuk expressed her condolences to their families.

“This is an absolute tragedy that two people going about their normal business, just as we all do, have lost their lives in such tragic and horrific circumstances,” she said.

“I really feel for their families and I express our deep condolences.”

One local, Rikki Saunders, did not know them but left two pairs of baby socks at the site.

“It really hit home – we are not far off that where we are,” he said.

“It’s not two lives lost – it’s a family, it’s an expecting family.

“It’s just innocence that will never see the light, that’s the hardest part.”

The Alexandra Hills community rallied to find Frankie, who took off after the crash. Photo: Supplied

The couple’s two dogs ran from the scene. One was found by the community last night and taken to a local vet.

A Facebook group was set up on Wednesday morning to find the second dog, Frankie, with dozens of people setting out to search.

She was found about midday (Queensland time), with the administrators of the group saying they had been placed in a “loving home”.