With security in Iraq quickly deteriorating, the United States on Wednesday pledged "any appropriate assistance" to help the Iraqi government fend off a rapid military advance by Islamist militants.
Militants from the Islamic State in Iraq and the Levant (ISIL) hours earlier overran the city of Tikrit and closed in on Iraq's biggest oil refinery in the town of Beiji, a day after seizing Iraq's second-largest city, Mosul.
By late Wednesday, militants had reached the edge of Samarra, an important Shi'ite shrine almost 113 kilometers, or 70 miles, north of Baghdad, The New York Times reported. The militants threatened to destroy the shrine unless government forces left.
Witnesses said militants have taken over several Tikrit police stations and the governor reportedly is missing. Tikrit, the hometown of fallen Iraqi dictator Saddam Hussein, is less than 200 kilometers, or 124 miles, from Baghdad and the central government.
The State Department has had no confirmation of news reports that militants were heading for Baghdad, spokeswoman Jen Psaki said in a news briefing. "It is a very fluid situation on the ground," she added. "We are of course very concerned about the deteriorating situation."
Militants still control Mosul
Militants continue to hold Mosul, as both Prime Minister Nouri al-Maliki and Ninevah Provincial Governor Athil Nujeifi urged residents to fight to retake it.
Maliki blasted Iraqi military officials who deserted their posts and fled Mosul, claiming in a speech Wednesday that they were part of a plot.
Earlier on Wednesday, the International Organization for Migration said Wednesday that fears of further violence in Mosul forced 500,000 people to flee their homes. It said the displaced either moved across the city or fled to other parts of Ninevah province or the neighboring Kurdish province of Irbil.
Turkish government sources said militants have seized the Turkish consulate in Mosul, kidnapping at least 48 people, including the Turkish consul, staff members, guards and three children. The militants already had abducted 31 other Turkish citizens, truck drivers who were being held at a Mosul power station.
Psaki said U.S. Secretary of State John Kerry and Turkish Foreign Minister Ahmet Davutoglu had discussed the situation by phone.
"We are in touch with the governments of Turkey and Iraq and stand ready to provide any appropriate assistance,'' she said.
Washington this year already had increased training of Iraqi security forces and expedited military equipment supplies, Psaki said.
"We are working with Iraqi leaders from across the country to support a coordinated response," Psaki said, "and you can expect we will provide additional assistance to the Iraqi government to combat the threat from ISIL.'
At the United Nations in New York, Davutoglu warned Wednesday that any harm to Turkish citizens would be met with the "harshest retaliation."
Global oil prices climb
Militants had entered Beiji, set fire to the police station and courthouse, and driven out some 250 men guarding the refinery. With news of the seizure and threat to Iraq's oil supply, global oil prices climbed to $110 a barrel.
Separately, at least 16 people were killed in a suicide bombing in Baghdad. The attack took place at a tent where people had gathered in Sadr City's Shi'ite neighborhood.
Iraq's Foreign Minister Hoshyar Zebari said Wednesday that Iraq's leaders must unite to face what he called a "serious, mortal threat" facing the country.
The militants' seizure of Iraqi cities and their swift advance southward constitute a stunning defeat for the country's Shi'ite-led government.
Hundreds of fleeing soldiers reportedly tore off their uniforms and fled their posts for the safety of nearby Kurdistan. One soldier told Iraq's al-Sharqiya TV that he had come "face-to-face with vicious Pakistani fighters" and "felt incapable of pushing them back."
Declaration of emergency sought
Maliki, saying the country is "undergoing a difficult stage," asked parliament to call an urgent session to declare a state of emergency.
The parliament's speaker, Osama al-Nujaifi, characterized the militants' takeover of Mosul as "a catastrophe by any measure" and described the scene there.
"When battles intensified inside the city of Mosul, the [Iraqi] forces abandoned their weapons and the commanders fled, leaving behind weapons, armored vehicles," al-Nujaifi said. "Their positions were easy prey for terrorists, even Mosul airport. Planes and command positions -- all of them have fallen, in addition to weapons caches. Also, prisons were stormed and criminals have been set free. What happened is a catastrophe by any measure."
The attackers were armed with rocket-propelled grenades and anti-aircraft weapons. Retreating Iraqi troops set fire to fuel and ammunition depots to keep the insurgents from using them.
Al-Qaida group defies control
The takeover of Mosul was the latest blow against the Iraqi government's attempt to control the growing insurgency by ISIL, an offshoot al-Qaida group. Earlier this year, the group took over another Iraqi city, Fallujah, and government forces have been unable to reclaim it after months of fighting.
To the west of Mosul, the militants have seized control of parts of eastern Syria in their fight against Syrian President Bashar al-Assad. The insurgents are seeking to establish an Islamic state with the regions they control in eastern Syria and western Iraq.
Iraq is dealing with its worst violence since 2008, with the United Nations reporting that approximately 4,500 people have been killed this year. More than 900 of the deaths occurred last month.
Related video by Sebastian Meyer, "ISIS Takeover in Mosul Displaces Thousands"
Some information for this report came fron Reuters. VOA News' Edward Yeranian also contributed from Cairo, Egypt.