Fighting in the Yemeni city of Aden has intensified as Houthi rebels try to seize the key government stronghold.
Witnesses have reported bodies lying in the street after intense rebel shelling and sniper attacks.
The fierce fighting has continued despite seven nights of airstrikes by a Saudi-led coalition.
Meanwhile, local officials in the port city of Mukalla said al-Qaeda militants had stormed a prison there and freed at least 150 detainees.
Officials said that among those freed was a senior figure in the regional wing of al-Qaeda.
Wednesday morning brought reports of fresh clashes between Houthi rebels, supported by troops loyal to the former President Ali Abdullah Saleh, and local militia.
Last week the rebels appeared to be hours from overrunning the city. This forced President Abdrabbuh Mansour Hadi to flee to Saudi Arabia and spurred it to begin airstrikes.
As the fighting continues, concern over casualties has risen.
A spokeswoman for the aid agency Medecins Sans Frontieres (MSF) told the BBC that its hospital in Aden had received more than 500 injured people from all sides in the conflict over the last two weeks.
Coalition spokesman, Gen Ahmed Asir, told the BBC's Frank Gardner in Riyadh that "it was a hard task to target" the rebels.
The coalition was "using all intelligence resources to make sure they are not hitting the wrong target. We do not hit any target without making sure it is a Houthi or troops loyal to former President Saleh," he said.
The UN has also expressed alarm at the rising number of civilian deaths in Yemen.
President Hadi had taken refuge in Aden after the Houthis took full control of the capital Sanaa in January and placed him under house arrest.
On Wednesday, at least 35 workers were killed by a blast at a dairy factory in the Red Sea port city of Hudaydah.
There were conflicting reports about the cause of the overnight explosion but witnesses said coalition aircraft hit warehouses belonging to the factory.
The latest violence comes as dozens of Yemenis are reported to have crossed the Gulf of Aden in small boats to get to Somalia and Djibouti to escape fighting and airstrikes on the city of Taez.
The arrival of the Yemeni refugees reverses a decades-old trend in which thousands of Somalis have sought sanctuary in Yemen to escape their own country's violence.
The Houthis have said their aim is to replace President Hadi's government, which they accuse of being corrupt.
The Houthis: Zaidi Shia-led rebels from the north, who seized control of Sanaa last year and have since been expanding their control
President Hadi: Fled to Saudi Arabia after rebel forces advanced on his stronghold in the southern city of Aden
Al-Qaeda in the Arabian Peninsula: Seen by the US as the most dangerous offshoot of al-Qaeda, AQAP opposes both the Houthis and President Hadi.
Islamic State: A Yemeni affiliate of IS has recently emerged, which seeks to eclipse AQAP