Katy Perry hailed first responders across the US after collapsing on 'American Icon' amid a gas leak.

The 35-year-old pop star - who is engaged to actor Orlando Bloom - collapsed in the middle of filming auditions in Sunriver, Oregon, and Katy has now taken to Twitter to praise all of the first responders throughout the country.

Alongside a video of Katy hugging members of the emergency services and singing along to Lionel Richie's 'All Night Long (All Night)', she wrote: ''Big shout out to all of our first responders around the country - thanks for risking your lives every day...and all night long #AmericanIdol (sic)''

Katy and her fellow judges - Luke Bryan and Lionel Richie - were just about to begin an audition when Katy detected a ''pretty intense'' gas smell and began to feel unwell.

After the scenes aired on 'American Idol', Katy joked about the gas leak and how it reminded her of one of the other judges on the show.

The pop star quipped: ''FIRST OF ALL, do you know how many texts I got from my mom and dad about the texts they got asking if I was okay #gasleak #AmericanIdol

''SECOND OF ALL, I'm used to smelling gas at the desk but it's usually @lukebryanonline [wind emoji] (sic)''

During the episode, Katy fell on the floor, saying: ''I have a slight headache from it. Oh, it's bad. It's really bad.''

Fire trucks and ambulances soon arrived on the scene and outside Luke insisted: ''This is not a joke, there really is a gas leak.''

Katy - who is set to marry her movie star fiance later this year - then fell to the floor and said: ''I'm not feeling good.''