VANCOUVER -- Police are investigating after two 11-year-old girls and a teenager were allegedly groped near the Vancouver seawall this week.

Authorities said the alarming incidents all took place on Tuesday afternoon, and each involved a man riding a red and white bicycle.

"These girls were all near the seawall when a stranger on a bike grabbed them from behind and sexually assaulted them," Sgt. Steve Addison said in a news release Wednesday.

"Each victim did the right thing by telling a trusted adult and reporting the incidents to police so an investigation could be launched immediately."

The first groping incident happened when the two 11-year-old victims were walking together near Granville Island at around 4:30 p.m. A stranger biked past them and allegedly groped one girl from behind.

Authorities believe the same suspect followed them to West 6th Avenue and Birch Street, where he proceed to grope the second child.

About 30 minutes later, a 15-year-old girl was groped while running near Science World.

Police said they're still working to confirm whether the incidents were linked, and whether there may be more victims who have yet to come forward.

"We don’t know who is responsible for these crimes, but we’re working hard to gather evidence and identify the person or people responsible,” Sgt. Addison said. "Until we know more, we’re encouraging people to be aware and to immediately call 911 if they feel unsafe or have information about a crime."

The suspect in the first two incidents is described as an Asian man in his 30s who is about 5'4". He was wearing black-framed glasses with a blue hat, grey T-shirt and dark shorts.

The suspect in the attack near Science World is described as a man with dark hair who was wearing a dark ball cap, a grey shirt, grey or light-coloured pants, and a dark backpack.

Police asked anyone with information on the sexual assaulted to call the Vancouver Police Department's Sex Crimes Unit at 604-717-0601.