Lord Of The Rings star Liv Tyler threatened to call the police after confronting a mum yelling at her crying baby on Wednesday (17Jun09).
The actress was strolling along Santa Monica Boulevard in Hollywood when she heard the unnamed lady shouting and then realised her child was the target of her wrath.
An onlooker tells British newspaper the Daily Mail Tyler intervened and urged the woman to calm down.
The pair reportedly engaged in a blazing row, culminating in Tyler threatening to call the police and report the mad mum.
Tyler, who has a four-year-old son, called Milo, ended the row by checking on the distressed baby and walking away when she was satisfied the child was safe.