09/06/2012 02:53 EDT | Updated 11/06/2012 05:12 EST

Abraham Kiewiet: Vancouver Senior Charged In Lifeguard Sex Assaults

A Vancouver senior, who worked as a city lifeguard, has been charged with sexually assaulting four boys between 1971 and 1982.

Abraham Kiewiet was arrested at his home and charged with five counts of indecent assault on a male and five counts of gross indecency, Vancouver police revealed on Thursday.

Sex crimes investigators believe the alleged offences - against boys who were between 11 and 17 years old at the time - happened when Kiewiet was employed as a Vancouver Park Board lifeguard. He taught at the Vancouver Lifeguard School and volunteered as a coach at a YMCA aquatic safety program, said police.

Four victims, who are now in their 40s and 50s, came forward during the investigation that began this June.

Investigators say they believe there may be other victims who have yet to come forward and encouraged anyone with information to call them at (604) 717-0618.

The Vancouver Park Board called the charges "troubling" and said they're assisting with the police investigation.

The board highlighted its procedures such as criminal record checks before anyone is hired to work in a position of trust with children or vulnerable adults.