The tragic incident that happened at Brisbane's Story Bridge this morning was regarded as a murder suicide according to police.

Someone walking across the bridge saw the two dead bodies at around 3 a.m. and immediately reported to the authorities.

Reports say a man intentionally threw a child off the bridge and followed after causing their deaths. The man is believed to be the child's father. He rode his bicycle over the walkway on the outbound side of the Story Bridge.

Then he threw his child over the safety bar and jumped off. The bicycle was left on the sidewalk.

Based on the investigation, there were no court issues found regarding the child's custody. The police have already information close relatives of the victims.

Police and detectives have started to scour the parkland located below Brisbane's Story Bridge after the accident. The bridge's outbound lane was closed and blocked before 8 a.m., which disrupted peak hour traffic.

It was, however, re-opened due to heavy traffic at 7 a.m.

Joggers, walkers and cyclists were all asked to move out from the place where the incident happened. A mangrove area was enclosed with police tape while forensic scientists and other investigators look for physical evidence such as fingerprints.

The police blocked the crime scene with screens for privacy while loading the two bodies into a van. Detectives continued their monitoring while hunting for significant clues linked to the crime.

The police have set up 14 cameras focused on the Story Bridge and another 8 pan-and-zoom cameras also pointed directly to the structure. Residents have previously requested authorities to put screens on the sides of the bridge, which will prevent people from falling off.