This is stated in an article by Interior Minister Arsen Avakov for Censor.NET citing a diary of a terrorist from Odesa.
He noted that "during searches, an explosive device was seized: TNT sticks + plastic bricks + two alarms batteries + 10 batteries - all functional and stuck together with a tape. Separately [seized]: TNT blocks, detonator caps, electric detonators, canisters with explosives (fuel plus oxidizer), gun ammo. And also [seized] - notebook sheets with handwritten text: Diary of a terrorist. It is dated December 2014 to February 2015 - [it includes] amounts, dates, addresses, names, nicknames.
"Invaluable material for investigators," the minister wrote.
"But it is also a document of our time. The thoughts, fears, attempts to justify himself and the dirty deed, doubts. Yes, and doubts! It is a pity they did not force him to stop ...
"Now, behind bars, he will sober up, and, for the court, of course, he will repent. But inside? ..." Avakov wrote.
He noted that the text has very little mention of victims: "Only once there was some outright malicious joy: "two afronegroes were carried cold bodybags... " And not a word more... Apparently, it is not so simple to admit to yourself that you are a killer. And even the joy of the successful execution of the "job" is a short break from the shroud of constant fear ... They are very sincere, these notes: he was very scared. So scared that by the end he wrote only about explosives and money. No attempts to analyze," the minister stated.
The Minister quoted from the diary of the terrorist:
"10:45 p.m. We are waiting. 30 minutes have passed since we lit the fuse of the land mine, we already ate a chocolate bar each, moved into a courtyard, Ihor has washed down the remnants of his rations, but there is still no result.
"Nerves are all shot, I realize that something did not work.
The full "Diary of Odesa terrorist" can be read in Arsen Avakov's article for Censor.NET.