Latvia's prime minister unexpectedly resigned today, saying he can no longer lead the country after a supermarket roof collapse killed 54 people and sparked public outrage.

In recent weeks he has also run into difficulties with his ruling coalition, with several nationalist lawmakers demanding changes to how the country issues residence permits in exchange for support for next year's budget.

The announcement triggers the fall of the entire center-right government. But it is not expected to cause a political crisis or disrupt the country's economy, which over the past two years was the fastest growing in the European Union.

Police have opened a criminal investigation into the cause of the tragedy, which also wounded at least 40 people. Possible explanations for the disaster include a flawed design, substandard construction materials and corruption..

Many Latvians have expressed deep skepticism that the guilty parties will bear criminal liability and have gone so far as to demand that foreign engineers be invited to help the investigation.