Referees at an Edmonton rink were so afraid for their safety last week that they locked themselves in a dressing room until police came, a local hockey official says.

The referees waited until police could escort them to their vehicles, says Hockey Edmonton president Mark Doram.

The incident was just one example of recent "unacceptable" behaviour during a month that saw police twice called to local rinks and the organization suspend five parents.

Doram said he was so concerned he sent a stern warning to parents in an email on Feb. 24.

"The behavior is unacceptable," he wrote to parents of the 8,500 members of the hockey association. "Those involved lived up to what people think of as the 'Typical Hockey Parent.'

The hockey president told parents that city police have "more important calls in a night than coming to arenas to ensure the safety of officials, or breaking up fights between parents and/or coaches."

Incidents verbal

In an interview with CBC News on Monday, Doram said the type of conduct that led to the suspensions isn't widespread but happens at all levels above initiation. He said as far as he knows all the incidents have been verbal ones.

"The number in a month alarmed us," he said.

While many of the incidents involve parents and referees, other times there were arguments between parents and coaches, among parents from opposing teams, or in one case parents on the same team.

About 10 parents have been suspended this season for various reasons and lengths of time, including for up to a year, said Doram.

"What we want people to do is just be conscious of their emotions," he said.

Parents need to know where to draw the line and be careful not to become "verbally threatening," he said.

"We're going into a very emotional time now with city finals and provincials, and we just want people to act accordingly."

Many referees are teenagers themselves, he said, with some as young as 13 years old.

Doram said he has received emails from other sports organizations thanking Edmonton Hockey for sending the letter and drawing more attention to challenges they also face.

Since 2011, Hockey Edmonton has required a parent or guardian of all new association members to take a one-hour online course called Respect in Sport, which is intended to encourage better behaviour among coaches and parents.

"It might not be a bad idea that there is a refresher course mandated after every so many years of being within the sport," Doram said.