Three Iraqi children and two women from the same family were killed late Monday (September 28th) when a rocket targeting Baghdad airport, where US troops are stationed, fell instead on their home, the Iraqi army said.
Two more children severely injured in the attack later died from their wounds at the hospital.
The rocket was launched from al-Jihad neighbourhood in the west of the capital, the army said.
It is the latest in a string of attacks targeting US interests in Iraq, widely blamed on Iran-backed militias operating in the country.
The US has threatened to close its embassy in Baghdad unless the rockets stop.
The army accused "criminal gangs and groups of outlaws" of seeking to "create chaos and terrorise people".
Between October and July, at least 39 rocket attacks targeted US interests in Iraq. Almost the same number again have taken place since.
In total, four soldiers -- two British, one Iraqi and one American -- along with a US and an Iraqi contractor have been killed in the attacks, while several civilians have been wounded.
Twitter accounts supporting Iran regularly praise the attacks, but that was not the case Monday, when no group immediately claimed responsibility.
Half a dozen previously unheard-of factions have claimed similar attacks in recent months, under the banner of "Islamic resistance".
But experts say they are a smokescreen, and that they include former members of pro-Iran factions of the Popular Mobilisation Forces, a state-sponsored network close to Tehran.
Iraqis condemn attack
A video and photos posted online show the destroyed house and stains of blood. It features a family member who says this was not the first time that rockets intended for the airport landed near their home.
A wave of anger and condemnation has swept the Iraqi street following the attack.
"This should not pass without accountability... it is a major crime that claimed the lives of innocent women and children. What have they done wrong to be killed like this?" said Wissam al-Obeidi, a resident of Baghdad's al-Doura neighbourhood who asked to use a pseudonym.
"We do not feel safe anymore, even inside our own homes, because of the actions of these unruly groups," he told Diyaruna.
While previous missile attacks have led to casualties and material damage to citizens' homes, Monday's incident was the bloodiest.
"We are living in a nightmare because of the repeated bombing of the airport," said Haider, a resident of al-Furat neighbourhood near Baghdad airport, who only gave his first name.
The government must intervene to "prevent new massacres at the hands of these criminal gangs", he told Diyaruna.
'Investigation must yield results'
In a statement Monday, the army said prime minister Mustafa Kadhemi has ordered an immediate investigation into the incident to track down the perpetrators, "regardless of their affiliations and ties, so they may be handed the most severe punishment".
Kadhemi ordered the arrest of members of the security force responsible for monitoring the area from which the rocket was launched for "failing" to perform their duties, it added.
He also urged all security services to step up their intelligence efforts "to curb these crimes that terrorise citizens".
The investigations must lead to the quick capture of the perpetrators of this crime, said Katah Najman al-Rikabi, member of the parliamentary security committee.
"We have repeatedly said that authorities must enforce the law and protect citizens and state institutions from uncontrolled weapons," he told Diyaruna.
They must step up pre-emptive operations in the areas these rockets are launched from "to prevent future attacks by elements who use hit-and-run and guerrilla warfare tactics", he added.
Al-Rikabi called on the government to quickly "disclose the results of the investigation into the killing of this family" and of all investigations into previous security breaches and assassinations.