Sydney, Jul 1 (IANS): Australian Police are currently investigating the cause of a serious two-vehicle traffic crash after three female passengers aboard a bus were killed in Queensland during the weekend.

Around 11:00 a.m. local time on Sunday, a four-wheel drive towing a caravan and a bus crashed on the Bruce Highway at Gumlu, a coastal town located in the state's north, reported Xinhua news agency.

"Three passengers on the bus died at the scene, including a woman in her 30s, a woman in her 20s, and a 56-year-old Townsville woman. Multiple other people were taken to hospital, some with serious injuries," Queensland Police said in its latest statement on the accident.

Following the crash, the Bruce Highway was closed in both directions at Gumlu before reopening to traffic at midnight.

Queensland Police Superintendent Graeme Paine provided an update to the local media outlet ABC News Breakfast on Monday morning, saying that officers are working to confirm the identities of a female in her 30s and another in her 20s, with several people still receiving treatment in the hospital.

"One of those is in critical condition. So there are certainly some concerns held for the safety of that person," Paine noted.

According to the superintendent, the incident occurred in a zone that has a speed limit of 100 km per hour. The bus was travelling northernly on the highway and the four-wheel drive was heading in a southern direction.

"The impact that had occurred, it pushed the bus across to the railway line, hence we had the closure of the railway line at the time," he added.

Given that an incident of this nature appeared "very complex," the officer didn't touch upon the cause of the accident, but stressed the necessity of going through "a holistic investigation."

"Our specialist crash investigators have forensically examined the scene. They are currently interviewing additional witnesses and there will be further analysis of evidence," said Paine.

Reports from the Queensland Ambulance Service suggested that a total of 35 patients were assessed at the crash site.

"Two patients with life-threatening injuries were airlifted to Townsville Hospital, and two patients with life-threatening injuries were airlifted to Ayr Hospital and four stable patients were transported by road to Ayr Hospital. Sadly, three people were deceased at the scene," said the local emergency agency.

In addition, 24 other patients were identified with minor injuries and declined hospitalisation.

With a population of 124, Gumlu is a remote locality in the Whitsunday region, lying 1,223 km north of Queensland's capital Brisbane, with Bruce Highway as the major artery connecting a slew of towns along the state's eastern coast.

Whitsunday Mayor Ry Collins described to ABC Radio that the section of the highway could be challenging as it "feels like a country road."

"There's no shoulder on the road. It is a fairly open section so I'd imagine the vehicles coming either way would have been able to see each other but there's obviously been something happened here where one's veered into the other's lane," said Collins.