Oopsie.

(Bloomberg) — Islamic militants disguised themselves as street cleaners to carry out two bomb blasts last month in Atyrau, the capital of Kazakhstan’s biggest oil- producing region, the Prosecutor General’s Office said.

The explosions near buildings housing local prosecutors and the city’s mayor were part of “an action plan to frighten law- enforcement and other state officials,” the Astana-based office said in a statement on its website today. The attackers dressed in the uniform of communal-service employees while planting the bombs, according to the statement.

Prosecutors confirmed that an armed offshoot of the Jund al-Khilafah group trained the four men behind the blasts. One of them died when a bomb he was carrying exploded prematurely.

Kazakhstan, a predominantly Muslim former Soviet republic that borders Russia and China, has seen an upsurge of attacks in its oil-rich regions.