SANAA (Agencies) - A motorcycle bomb exploded amid a crowd of namazis leaving Bin Salman mosque in Yemen's northwestern town of Saada after Juma prayers, killing at least 18 people and wounding about 45, according to military sources at the site. The attack on the mosque, located near an army barracks, raised fears of an escalation in violence between the government and Shia fighters whose insurgency in the mountainous province of Saada has claimed thousands of lives since 2004. There was no immediate claim of responsibility, but a local official told AFP the attack bears the hallmarks of the Huthis. "Terrorist criminal followers of the terrorist Abdul Malak al-Huthi are behind this ugly crime," an Interior Ministry official told the Saba state news agency, referring to the rebels' field commander. According to BBC, Huthi, the leader of a Shia rebellion in the area, denied responsibility for the blast. "We deny completely any role in this incident. It is not part of our ethics to target any mosque or any worshippers at all." In a statement received by AFP, he condemned the "tragic" attack and called for "searching for the truth objectively" in order to identify the perpetrators. The rebel chief also accused unnamed parties of seeking to thwart peace efforts in Saada and urged natives of the province to close ranks. Military sources said the dead were mostly soldiers, but they also included beggars - women and children - who had been waiting outside the mosque. Most of the injured were soldiers. Some witnesses said the attack might have targeted the mosque's Imam, Askar Zuail. Witnesses said the Imam had just left the mosque and was not hurt. Local sources said the Imam is an aide to Ali Mohsen, military commander of the northwestern region who has led the battle against the insurgents. The Interior Ministry later said it had arrested a number of armed men on suspicion of being the culprits after they were stopped at a security checkpoint in the Saada region, Saba reported. It said there was evidence the suspects had sat in their car outside the targeted mosque during the prayers, and fled quickly after the explosion. Mosques in Yemen cater for both the majority Sunni community and the Zaidis, a Shia offshoot, but are usually identified by the sect of their prayer leader. On Tuesday, seven soldiers were killed and 20 wounded when their convoy was ambushed by rebels in Saada. The renewed violence comes despite recent efforts to implement a peace deal between the government and the rebels brokered by Qatar in June 2007. The agreement, under which the insurgents would lay down their arms, was revived during a meeting between the two sides in Doha in February. Qatari mediators were still in the capital Sanaa on Friday. Yemeni authorities have rushed military reinforcements to Saada in the past few days. The rebels have been fighting to restore the Zaidi imamate, which was overthrown in a 1962 republican coup in Yemen, one of the world's poorest countries. The insurgents are known as Huthis after their late commander, Hussein Badr Eddin al-Huthi, who was killed by the army in September 2004. Hussein was succeeded as field commander by Abdul Malak, his brother. The rebels reject President Ali Abdullah Saleh's regime as illegitimate, although Saleh himself is a Zaidi. The Zaidis are a minority in mainly Sunni Yemen but form the majority in the northwest. Yemen, an Arabian peninsula country with a tribal structure, has been repeatedly hit by violence in recent weeks. Two attacks in Sanaa in March and April targeted US interests and were claimed by the local wing of Al-Qaeda. A schoolgirl and policeman were killed in one of the attacks. On Wednesday, two car bombs exploded inside the compound of customs headquarters in Sanaa, but there were no casualties.