"It was an intense night of bombing and the windows shook," said a foreigner working for an international aid organisation in Sanaa.
"People want to leave but there are no flights out of Yemen," she said.
According to an AFP photographer, it was the most violent night of raids heard in the capital since the operation began late Wednesday.
He said the bombing was felt throughout the night until dawn.
The airstrikes apparently mainly targeted arms depots and other military facilities outside Sanaa, witnesses said.
Sunni-ruled Saudi Arabia has vowed to do "whatever it takes" to prevent Hadi's overthrow, accusing Shiite Iran of "aggression" and backing the Huthi rebels' power grab.