Jennifer Lopez had to reprimand her children right before a concert on Friday (17.08.12).

The 'On the Floor' hitmaker usually spends the moments before a show alone in her dressing room but had to step out in the Los Angeles Staples Center after four-year-old twins Max and Emme - her kids with ex-husband Marc Anthony - caused chaos backstage playing on scooters.

An onlooker said: ''[They were] speeding around the green room area and causing a ruckus, almost running over people and running into things.''

Staff were trying to calm the children but to no avail, prompting their famous mother to be called to assist - and the kids calmed down right away without her saying a word.

The source added to the New York Post newspaper: ''[She came out and] gave Max and Emme that 'mom' look to reprimand them.

''She got her kids off the scooters and back into their room.''

A spokesperson for the star said Jennifer was being a ''loving and responsible mom'' in taking action.

The representative said: ''Jennifer's family has a private and secure area backstage at each show. Jennifer is a loving and responsible mom, she would never put her children or others in a Dangerous situation.''