Afghan authorities are searching for Abdul Saboor, a 25-year-old Afghan man who is suspected of shooting and killing two U.S. officers in Kabul on Saturday.
Saboor is believed to have walked into a secure room used by two American military advisers and shot both in the head. He then escaped from the ministry and remains at large.
Afghan officials describe Saboor as a man who never never suggested any radical tendencies, leading them to assume that he was inspired by the burning of Qurans by U.S. troops last Tuesday. The U.S. government says the books were burned inadvertently.
Saboor is a driver for an Afghan officer in the Ministry of Interior's operations unit -- the same unit where the American advisors worked, according to Afghan officials.
He likely knew the two Americans, but it's not clear if he ever interacted with them.
Saboor had gone through all the checks that gave him permission to carry a gun inside the ministry, Afghan officials said.
Afghan officials have found no evidence that he has ties to insurgent groups, but have discovered that he took part in religious studies in a madrassa in Pakistan, leading some to fear he may have some kind of past connection to members of the Taliban.
Before the shooting, some of Saboor's colleagues saw him in the hallways and said he ignored their greetings and acted strangely, the Afghan officials said.
In total, more than 30 people have died and 100 have been wounded in the protests since the Qurans were burned, including four U.S. soldiers killed by Afghans.
While these Afghan on American killings are rare, they are growing.
On Saturday, Gen. John Allen, commander of the ISAF, responded to the attack by pulling all foreign advisers out of Afghan ministries. There are hundreds of advisers from 49 coalition countries assigned to various ministries.
"I condemn today's attack at the Afghan Ministry of Interior that killed two of our coalition officers, and my thoughts and prayers are with the families and loved ones of the brave individuals lost today," Allen said Saturday. "We are investigating the crime and will pursue all leads to find the person responsible for this attack. The perpetrator of this attack is a coward whose actions will not go unanswered."
Afghans Protest Quran Burnings
Since Tuesday the country has been roiled by protests over the American military's burning of religious texts, including Qurans. NATO is investigating the burning.
A public apology by President Obama on Thursday has failed to stop the unrest.
Just hours after the attack at the Interior Ministry Saturday, Afghan President Hamid Karzai's office released a message from the nation's top religious council demanding that the U.S. "guarantee" no further desecration of Qurans.
Today, at least two people were killed in protests.
Outside of Kunduz City, where protesters tried to storm the UN compound Saturday, one person was killed when police fired into a crowd.
In that same protest, somebody threw a grenade into a military base, injuring two American soldiers, according to Afghan officials.
In nearby Samangan, another group of protesters blocked the main road to Kabul for six hours. One person was killed there.
On Thursday, two U.S. soldiers were gunned down by a member of the Afghan Army at a base in eastern Afghanistan as civilians protested the Quran burnings outside the base.
ABC News' Aleem Agha, Luis Martinez and Martha Raddatz contributed to this report.