At least a dozen women interrupted a major economic speech by Donald Trump by jumping up and shouting in a co-ordinated effort to disrupt the Republican presidential nominee's remarks.
One at a time, women seated throughout the audience stood up and yelled "Mr Trump", but their continued shouts were quickly drowned out by boos as security led them from the room.
An organisation called the Michigan People's Campaign said it was behind the protest. It was hard to hear the women, but the group said they were yelling at Trump about jobs and his comments on women.
In an apparently separate incident, one man also stood up towards the end of the event and yelled that Trump has "tiny hands". That was believed to be in reference to a sexually tinged comment by primary rival Marco Rubio.
Protesters have occasionally disrupted Trump's larger rallies, where members of the public can enter, but this was the first time he has faced such sustained resistance at a policy speech delivered to a private group.
He was speaking to the Detroit Economic Club and most people in attendance were club members or their guests.
Trump largely stayed on message as security removed the protesters. He paused to let the disruption subside several times and occasionally continued speaking through protesters as the audience offered him applause and standing ovations.
"The Bernie Sanders people have far more energy and spirit," Trump said after one woman was taken from the room.