Baghdad ? Bombers struck a pet market in central Baghdad and a police checkpoint in the northern city of Mosul on Friday, killing 28 people in two of the deadliest attacks in weeks.

The first blast occurred before 9 a.m. when a bomb hidden in a box of small birds exploded as Iraqis were strolling past animal stalls and bird cages at Baghdad’s al-Ghazl market. The market had recently re-emerged as a popular venue as security has increased in the capital.

Police and hospital officials said at least 15 people were killed and 56 wounded, including four policemen. Another 13 people were killed in the Mosul attack, police said.

The Baghdad bombing was the deadliest in the Iraqi capital since Sept. 9, when a suicide car bomber killed 15 people in Sadr City.

The ability of extremists to penetrate the security surrounding one of Baghdad’s most popular shopping areas tempered the budding sense of hope in the capital after years of turmoil.

The blast sent dogs scattering in the streets and neglected chicks chirping near pools of blood as vendors rushed to help the wounded.

“Today, the market was very crowded and we were happy about that,” said Amir Aziz, a 22-year-old pigeon vendor who was wounded by shrapnel. “The Iraqi security officials have deceived us by their statements that the situation is 80 percent better. People believed them and began to go out thinking that it would be safe. I think that the situation will become worse again.”

The Iraqi military spokesman in Baghdad urged patience, insisting that security forces were gaining the upper hand but acknowledging that “pockets of terrorists” still exist.

“People have to stay alert and continue cooperating with us so as not to give the terrorists any opportunities to carry out such cowardly operations,” Brig. Gen. Qassim al-Moussawi said.

The Mosul blast happened as vehicles were lined up for inspection at a checkpoint. Ten civilians and three policemen were killed, police Brig. Gen. Mohammed al-Wakaa said.

“My car was the 15th in line to be checked,” said 32-year-old Akram Hazim. “Suddenly I heard a big explosion and the windshield shattered all over me. Some people dragged me outside the car and took me to the hospital.”

U.S. commanders say attacks are down 55 percent nationwide since June because of American success in subduing Sunni and Shiite extremists since President Bush ordered nearly 30,000 reinforcements to Iraq this year.

But U.S. officials have cautioned that the extremists have been bloodied but not defeated. The bombings occurred one day after 18 people were killed in an al-Qaida attack in south Baghdad and about 10 rockets or mortars slammed into the U.S.-protected Green Zone in the capital.

Despite the uptick in violence, November appeared on track to be the fourth month in a row to see a decline in the total number of Iraqi deaths, with at least 517 reported so far compared with 911 in all of October, according to an Associated Press tally.

“We fully expected al-Qaida in Iraq to try and hurt and kill people,” military spokesman Maj. Brad Leighton said. “Have we diminished their capability to do that? I think we have. But they’re still out there and they’re still a viable enemy.”

“Even though the general trend is down for violence, you’re going to see some peaks and valleys in that,” he added.

In all, at least 45 people were killed or found dead Friday across the country, according to police reports.