Earlier in the day a source with the team investigating said three people had been detained over the incident at Cherkizovsky market in the northeast of the city, but Yury Syomin said put the figure at two and suggested the case could be solved soon.
"We have very strong evidence that the suspects were involved in this explosion. We are not disclosing their names and details in the interests of the investigation," he said.
Syomin said earlier Friday that a turf war between commercial groups was at the center of investigations, but terrorism was also under consideration. One witness said he had seen a bag being brought to the scene before the explosion.
"We saw three people leave a bag at the market's cafe," the witness said. "Knowing security measures, especially with regard to unattended items, two market employees ran after the people who left the suspicious bag. At precisely that moment it exploded."
Syomin said the explosive device, which he said was the equivalent of a kilogram of TNT and went off at 10:27 a.m. Moscow time (6:27 a.m. GMT), had probably caused a liquefied gas cylinder to detonate. Two bangs were heard, although police earlier said there had only been one explosion.
Like most markets in Moscow, many traders are from the North Caucasus region and former southern Soviet republics. Prosecutors initially investigated a turf war as being behind a September 2000 bombing that killed 13 in an underpass in the heart of Moscow, although the mayor suggested the "Chechen trace" could also be seen in the incident.
