Saudi Arabia-led Arab coalition fighter jets bombed outposts of Houthis and pro-Saleh forces late on Sunday.
The jets targeted a police camp in central the capital, eyewitnesses said.
Sounds of strong explosions as well as ambulance sirens were heard.
The fighter jets continued flying over the capital till the wee hours of Monday.
Coalition forces have been bombing Houthi-held areas since March in support of the exiled government, which was driven from power in March by Houthi fighters who have since taken over much of the country.