Law enforcers estimate that the explosion that occurred outside of the office of the Ukrainian Security Service (SBU) in Odesa on Sunday was equivalent to 8-10 kilos of TNT, a source in law enforcement told Interfax-Ukraine.

"The explosion outside of the SBU office was heard in most parts of Odesa. The burst wave broke windows in a radius of several blocks away from the epicenter. Our tentative estimate is 8-10 kilos of TNT," the source said on Sunday morning.

The source said a caseless bomb was used. He added that it was the most powerful explosion staged recently.

Earlier reports said that a bomb exploded outside of the SBU building in Odesa Sunday morning damaging the building and windows in nearby houses.

Nobody was killed or hurt in the incident.