The incident happened in a building here and those present said that the 29-year-old actress remained calm throughout the ordeal, reported New York Post.
"They were stuck in the elevator for 45 minutes, and it became very hot in there, but Mila and everyone else remained calm. There were fire trucks outside, and firefighters helped them get out," a source said.
Kunis is currently dating 'Two and A Half Men' star Ashton Kutcher. They first met 14 years ago when they co-starred in hit sitcom 'That 70s Show', and the pair rekindled their spark after he split from wife Demi Moore.