Three police officers and one civilian were killed Monday in armed attacks on a police station and a security building in Kazakhstan's largest city Almaty.

Police said they have disarmed and arrested two attackers but have not said whether others were involved in the assaults in the country's financial capital.

Speculation mounted over the motives of the gunmen, with some media reports describing them as radical militants.

President Nursultan Nazarbayev, 76, chaired an emergency meeting of his security council in response to the shootings, his press service said.

The first detained man is accused of killing a local resident during a carjacking and attacking the Almalinsky police station in broad daylight, then shooting dead a police officer and seizing his gun, the interior ministry said.

The suspect then shot dead two officers as they gave chase before being arrested.

The health ministry said eight people had been admitted to hospital.

"According to preliminary information, the detained man is a 27-year-old man with previous convictions," the interior ministry said, adding that he was also suspected of murdering a woman at the weekend.

The police have not provided any details about the second suspect.


'Critical threat'

Two videos were widely shared on social networks showing a black-clad man roaming the streets of Almaty armed with a machinegun.

Kazakhstan's National Security Committee a red alert warning of a "critical" threat following the attacks on one of its buildings in Almaty and the nearby police station.

"I clearly heard shooting. Several shots were fired in quick succession. I was driving close to the police station at the time," a 40-year-old man who only gave his first name, Kanysh, told AFP.

Kazakh media reported a shootout at the security committee building, but said the attack was repulsed and the building cordoned off.

Police called on Almaty residents to stay in their homes but denied local media reports of further assaults.

Several major banks and supermarkets closed their doors following the attacks, an AFP correspondent in Almaty reported.

The city's airport tightened security although it remained open, while the main railway station was cordoned off.

Kazakhstan was already on a lower "yellow level" terror threat alert after deadly shootings shook a town in the northwest in June.

Gunmen went on the rampage in Aktobe, near the Russian border on June 5, killing four civilians at two gun stores before trying to storm a military base with a hijacked bus, killing three soldiers.

In a statement on the Aktobe violence Nazarbayev called the gunmen "followers of radical pseudo-religious groups" and said they had operated on "instructions received from abroad"

At least 18 suspects were killed in police anti-terror raids following those attacks.

For much of its independence Kazakhstan was able to avoid the kind of political tumult seen in other countries in ex-Soviet Central Asia.

But growing social dissatisfaction in the majority-Muslim nation has grown as the economy reels from low oil prices and the economic slump in neighbouring Russia, a strategic ally.

Almaty, a city in the south with a population of around 1.5 million people was Kazakhstan's capital until 1997 when the northern steppe city of Astana took over that role.