Baghdad, Iraq (CNN) -- Assassinations and attacks in Iraq killed at least five people on Tuesday, as U.S. troop levels dropped to their lowest numbers since the war began and the country was praised for a precipitous drop in violence.
Gunmen using silencers killed Ahmed Hassan, an official with the Sadr City Municipal Council, in an eastern Baghdad neighborhood, police said. Hassan was standing outside his house Tuesday afternoon when he was gunned down in a drive-by shooting, police said.
In western Baghdad, Mithaq Salman Falih, a member of the Radhwaniya Awakening Council, was killed by a bomb attached to his car, police said.
The awakening councils, also known as the Sons of Iraq, were established by Sunni Arabs to reduce violence and provide security for residents in certain areas of the country. Council members are frequent targets of al Qaeda in Iraq.
In other incidents Tuesday, a roadside bomb exploded in the western Baghdad neighborhood of Ghazaliya and wounded two bystanders, police said.
In the northern city of Mosul, gunmen tossed a hand grenade at an Iraqi army patrol, wounding three soldiers, a policemen and a civilian, police said.
And a suicide car bomber targeted an Iraqi police checkpoint in western Baquba on Tuesday evening, killing at least three people and wounding 11 others. Police officers were among the casualties.
Minutes later, as Iraqi security forces gathered to investigate, a second suicide bomber tried to drive toward the investigators, but Iraqi security forces shot and caused the car to explode, killing the bomber but causing no other casualties.Baquba is about 60 kilometers (40 miles) north of Baghdad.
Overall violence in Iraq has declined considerably over the past two years compared to the height of the sectarian war between 2005 and 2007, but security remains an issue in Iraq as U.S. combat troops depart the country.
The number of U.S. troops in Iraq has now fallen below 50,000 -- the lowest level since the U.S-led invasion in 2003, the military said Tuesday.
The drop comes ahead of President Barack Obama's deadline to bring down troop levels by August 31. The military said U.S. troops will now transition from Operation Iraqi Freedom to Operation New Dawn, effective September 1. In this phase, the United States will help train Iraqi security forces until the end of its mission in December 2011.
Speaking to veterans Monday, Vice President Joe Biden said violence in Iraq has dropped so much that some soldiers "would not recognize" the country today.
The roughly 650,000-member Iraq security force is "already leading the way to defend and protect [the] country," Biden said. "Some said that our drawdown would bring about more violence. Well, they were wrong," he told a gathering of the Veterans of Foreign Wars in Indianapolis, Indiana.
Iraqi officials, however, have noted a recent campaign of bombings and shootings in Baghdad targeting traffic police, Iraqi soldiers and local leaders.
CNN's Mohammed Tawfeeq contributed to this report.