Fifteen schoolgirls were killed in Yemen when their bus was caught up in a car bomb attack targeting a Shiite militia leader by suspected Al-Qaeda militants on Tuesday, officials said.
Another 10 people also died in the blast outside the home of Abdallah Idriss, a leader of the Shiite rebels known as Huthis, in the flashpoint town of Rada in central Yemen, a security source said.
A medical official confirmed at least 25 people had died.
The attack "bore the hallmarks" of Al-Qaeda, the security source told AFP.
The United States considers the Yemen-based Al-Qaeda in the Arabian Peninsula, or AQAP, to be the global jihadist network's most dangerous affiliate.
Also blaming Al-Qaeda, the Yemeni defence ministry condemned "this cowardly terrorist attack on the home of a citizen and a school bus".
The Sunni extremist AQAP has yet to claim responsibility, but last month its military chief Qassem al-Rimi vowed to launch fierce attacks against the Shiite militia.
"To the Huthis we say: brace yourselves for horrors that will make the hair of children turn white," he said at the time.
Yemen has been rocked by instability since the Shiite fighters seized control of the capital Sanaa on September 21.
The Huthis have since expanded their presence in western and central Yemen, but have been met by fierce resistance from Sunni tribes and Al-Qaeda militants.
The bombing comes after at least six Huthi militants were killed Friday in an attack on their checkpoint in Baida province, according to tribal sources.
Al-Qaeda claimed at the time that it had killed dozens of people in several attacks in Rada, which is located in Baida province.
- Saleh loyalists derail vote -
Signup to our newsletter and follow us on Facebook and Twitter!
Tuesday's attack was the second bombing to target Huthis in Rada in little more than a month.
On November 12, a suicide bomber killed dozens of people gathered at the residence of a tribal chief in the town.
The mixed Sunni-Shiite town has seen heavy fighting since the Huthis took over parts of it in October, with Al-Qaeda setting its sights on Rada.
State authority has weakened in the face of the rivalries on the ground.
Armed Huthis on Tuesday surrounded the defence ministry in Sanaa after having been denied access, a military source said.
Another group of Shiite militiamen broke into the offices of Ath-Thawra newspaper demanding the dismissal of the chairman of the board, Faisal Makram, a source at the official daily told AFP.
The militiamen said they were following orders from their leader, Abdelmalek al-Huthi, "to end corruption in all state institutions".
In another sign of its weakness, the government of Khaled Bahah lost a parliamentary vote of confidence on Tuesday.
Loyalists of ousted former president Ali Abdullah Saleh derailed the vote by leaving the assembly.
Lawmakers from Saleh's General People's Congress staged the walkout in protest after the party's office in the southern city of Aden was shut.
"The closure of the headquarters of our party in Aden by the security forces does not help the government," said Sultan al-Barakani, head of the GPC's parliamentary bloc.
Saleh remains influential in Yemen nearly three years after he was forced to step aside following a bloody year-long crackdown on Arab Spring-inspired protests against his iron-fisted rule.
He has been accused of backing the Shiite rebels.