CHICAGO (CBS) — Two families are suing separate trampoline centers in the suburbs over injuries to their children.

Xtreme Trampoline, at 485 Mission St. in Carol Stream, and Sky High Sports, at 6424 Howard St. in Niles, are named in the lawsuits.

In both cases, parents say their children suffered broken legs because the two centers failed to follow proper safety rules.

The parks were not supposed to allow more than one child to jump on a trampoline at the same time, but that rule was broken by both parks, according to the law firm Romanucci & Blandin. Attorneys say that was why the children were injured.

In a news release, Romanucci & Blandin emphasized that trampolines can be dangerous. While acrobats and gymnasts can perform handsprings, back flips and other tricks, youngsters risk serious injury when emulating them.

And in unsafe settings, even simple trampoline moves can be hazardous, the lawsuit said.

Last year, Xtreme Trampoline was highlighted in a CBS 2 investigation by Pam Zekman. She reported that between November 2010 and May 2011, there had been sixteen calls to the 911 center for an ambulance after injuries at the trampoline center.

One came from a mother who told the 911 operator, “my daughter…she fell directly on her neck, tingling in her arms, severe pain and she’s having trouble breathing.”

Erik Beck, the owner of Xtreme Trampolines responded in May of last year, “We’ve had 100,000 kids come through here so there are going to be injuries. I wish I could stop every one of them but there’s an inherent risk to jumping on trampolines.”

Beck says each customer must watch a safety video that includes house rules against sitting on a trampoline, more than one person on a trampoline, and “no double jumping.”

But when the 2 Investigators visited Xtreme Trampolines on a Saturday afternoon that month, an undercover camera recorded staff ignoring customers who were violating the rules. One kid was seen sitting on the trampoline while others jumped around. Another shot shows kids double jumping right in front of a staff member.

Customers were also allowed to jump into foam-filled pits, which experts say is unsafe.

A court date for the lawsuits was not immediately available.