Armed Yemeni tribesmen from the Popular Resistance Committees, supporting forces loyal to President Hadi, sit in the back of a pick-up truck on the outskirts of Marib dam on Wednesday.
Two Red Crescent volunteers were killed in an air strike south of Yemen's capital, the Red Cross said on Wednesday, as military sources said government forces expelled rebels from Marib dam to the east.
Qaed Faisal, 28, and Omar Fareh, 31, died along with several other civilians in a raid on Monday in Al-Swaida area of Taez province, said the International Committee of the Red Cross (ICRC).
It noted in a statement that the attack took place on the same day that more than 130 people were killed in a reported air strike on a wedding hall near Mokha on the Red Sea.
Riyadh has denied that a Saudi-led coalition which since March has been carrying out air raids on Shia Houthi rebels in Yemen carried out the attack on the wedding.
"Indiscriminate air strikes and shelling have been going on in many parts of Yemen for more than six months, causing huge suffering to the civilian population," the ICRC said.
Fuad al-Makhazy, secretary general of the Yemen Red Crescent Society, said eight of his staff and volunteers have now been killed.
Two Red Cross workers were gunned down in late August in rebel-held Amran province, north of Sanaa, in an attack which prompted the ICRC to suspend its operations in Yemen.
Houthi rebels, who control Sanaa and northern Yemen, swept south earlier this year, seizing second city Aden and forcing the government to flee into exile in Saudi Arabia.
But they have been pushed back north following months of fierce fighting and coalition air strikes in support of Yemeni government forces.
Embattled President Abedrabbo Mansour Hadi returned to Aden last week after nearly six months in exile in Riyadh.
On Wednesday, pro-Hadi forces who have set their sights on Sanaa made fresh gains in Marib province, east of Sanaa, capturing Marib dam and the surrounding hill, military sources said.
Abdulwahid al-Qibli, a Marib provincial official, said eight government soldiers were killed in the latest fighting with rebels.
Seven other soldiers were mistakenly killed and 22 wounded in a coalition air raid in the area, according to the military sources.
Also in Marib, a military official said two suspected Al-Qaeda militants were killed in an apparent US drone attack in Wadi Abida.