BAGHDAD: At least 21 people were killed and more than 70 injured Friday in two apparently coordinated attacks in Tikrit, home town of former dictator Saddam Hussein, officials said. The first explosion, a roadside bomb, targeted worshippers at a mosque, killing 15 and wounding 61, Raed Ibrahim, head of the health department in Salahuddin province, told Reuters. Hours later, when the injured were being treated in Tikrit hospital, a suicide bomber detonated an explosive vest there, killing six people and injuring 10, police said. The dead from the first blast, which happened as worshippers were leaving Friday prayers in the city 150 km (95 miles) north of Baghdad, included a senior provincial judge, and many local officials were among the injured. Friday's attack, inside a palace complex which belonged to Saddam, followed four bombs Thursday in Ramadi in western Iraq which killed at least six people and injured 17. Although overall violence in Iraq has fallen sharply since the peak of sectarian slaughter in 2006-2007, insurgents are still able to carry out lethal attacks eight years after the 2003 US-led invasion that toppled Saddam. Several attacks in Tikrit this year have caused a large number of deaths. In March, at least 53 people were killed when gunmen took hostages at the provincial council headquarters and fought security forces. In January, a suicide bombing in Tikrit killed up to 60 police recruits. Around 47,000 US troops still in Iraq are due to leave by the end of 2011 under a bilateral security pact, and Iraqi Prime Minister Nuri Al-Maliki's coalition government must decide in the coming weeks whether to ask Washington to keep some of them in place. US officials and senior Iraqi military commanders have said they believe some kind of continuing US military presence is necessary to ensure Iraq's security and defense needs.