Eleven people were killed and over 100 wounded Monday when a blast described as an act of terror tore through a metro station in the Belarus capital near President Alexander Lukashenko's headquarters.
The explosion left clouds of suffocating smoke inside the city's busiest metro station as bloodied passengers ran for the exits and others sat stunned on the floor inside, their shoulders covered in plaster.
Prosecutors said the blast was an act of terror and Lukashenko described it as a challenge for the authorities, but it was a mystery who was responsible for by far the most serious attack in the country's post-Soviet history.
Confirming the death toll of eleven, Lukashenko immediately called an emergency security session in which he placed the blame on unnamed political opponents, claiming they were seeking to destabilise his regime.
"I warned you that they won't let us live a calm life," the maverick president told a meeting that included the head of the former Soviet republic's feared security service, still known as the KGB.
Promising tough new security measures, Lukashenko said: "Guys, we have been presented with a serious challenge. We need an adequate response -- and it must be found."
The blast came amid rising political tensions in the country following Lukashenko's controversial re-election last year and also a severe economic crisis that has seen the government carry out a partial currency devaluation.
Lukashenko -- a leader once dubbed as Europe's last dictator by the United States who enjoys friendly relations with Iran -- said he could not rule out a foreign hand in the attacks.
"I do not exclude that this is a present from abroad but we must look at home too," he said, ordering the KGB chief to find the perpetrators as soon as possible.
Deputy Prosecutor Andrei Shved described the attack an an "act of terror" and said a criminal probe had been opened, Interfax reported.
"The external signs, the nature of the wounds people received, point towards an act of terror," an unnamed security source told Interfax. The health ministry said a total of 126 people had been wounded.
Belarus is normally considered a safe country and has never been touched by large-scale militant attacks such as those carried out by Islamist militants in Moscow.
On March 29, 2010, 40 people were killed and dozens wounded by two female suicide bombers during the morning rush hour on the Moscow metro and 37 were killed in an attack on the Russian capital's main airport this year.
Belarus has over the last half decade seen two more minor attacks blamed on nationalist fringe groups but never any strike that has resulted in fatalities.
Russian President Dmitry Medvedev swiftly called the explosion a terror act and offered Lukashenko the help of Russia's security service.
In power for one and a half decades, Lukashenko has prided himself on instituting law and order in Belarus, taking credit for stability that has come at the expense of a fierce crackdown on all forms of dissent.
The blast appeared to leave officials momentarily stunned, with some time passing before Lukashenko visited the site, laying flowers alongside his talismanic young son Kolya who accompanies him to almost all state events.
Stunned witnesses outside the station described scenes of mayhem, with shattering glass and thick smoke filling the halls as people returning home from work scrambled in panic.
"The glass started to shake and all the people suddenly fell silent -- it went silent in a flash. Everyone started telling each other to be quiet and not to panic," one woman said.
An AFP correspondent said the explosion paralysed underground traffic across the city of 1.8 million, resulting in traffic jams and grinding travel in the city centre to a halt.
Tens of thousands of people demonstrated through central Minsk on election night last December after Lukashenko's overwhelming victory was announced, with truncheon-wielding police moving in against the protesters and arresting hundreds.
The arrests have added to the Lukashenko regime's growing international isolation, with both the European Union and the United States announcing travel bans and economic sanctions against some Belarussian state companies.