A bomb exploded in a popular pet market in central Baghdad on Friday killing 13 people and injuring 57 people.

The bomb was hidden in a box of birds and it was described as being the deadliest attack in Baghdad in the last two months.

The incident occurred at the crowded Ghazil pet market, just before 9 a.m. After the blast, bystanders carried the victims to the ambulances.

This was the worst attack since September 26, when twin car bombs exploded in the district of Bayaa in southwestern Baghdad, killing 32 people. The attack is questioning the new-found confidence among Iraqis regarding the security in the country.

A few hours later a suicide car bomber hit the northern city of Mosul killing nine people, among them were six police officers.

According to Brigadier-General Mohammad al-Wagaa, head of the Mosul police operations room, the bomb struck a police patrol in southeastern Mosul killing five people.

Another bomb in the same area killed four people, Reuters reports.

In recent months level of violence decreased in Iraq since 30,000 U.S. troops were deployed in mid-June.

Attacks dropped by 55 percent, according to the U.S. military.

Normal life has returned to Baghdad since attacks dropped and thousands of Iraqis who fled their homes have been returning home.

People began to go to markets and to restaurants at night.

Ghazil stallholder Mohammed Abu Salim said: “The people were happy the last two weeks because the situation has improved. This explosion disturbs us."

The al-Ghazl market sells animals like monkeys, dogs, cats, sheep, goats, parrots, pigeons and tropical fish. It was the target of another attack on January 26, when 15 were killed due to a bomb hidden in a box of pigeons exploded.

On Thursday mortars and rockets hit the Green Zone, where the U.S. embassy and the Iraqi parliament are located, in the biggest attack against this area that is protected by the U.S. Nobody was killed, but there were unspecified injuries.