Two car bombs exploded near Dawlah Kabir Mosque in the Iraqi city of Ramadi, a police officer said on condition of anonymity, while a third car bomb went off in the city center, Khaama Press reported.
A short while later, a fourth car bomb exploded near a police building -- two suicide bomb blasts went off inside the same building later.
Earlier Sunday, a car bomb exploded in the Salahaddin province, killing one civilian and wounding 12 others.
The bomb exploded about 25 miles north of Tikrit, near a police station and judiciary center, the Kuwaiti news agency KUNA reported. The area had been sealed off by police out of fear of another explosion.
The attack came after Salahaddin officials filed an application seeking recognition of the province as a "region."
Hassan Mahmoud Al-Samarraei, spokesman for Salahaddin, said work on the referendum would continue for a week, at which point votes of citizens would be counted.
Iraq Interior Ministry officials said three people were killed and 22 others wounded in bombings at police stations throughout the country, Khaama Press said.