Three people have died in a series of bomb attacks at bus stops in the southern Russian city of Krasnodar, say police.
The blasts hit residential areas
At least 17 others were hurt.
A law enforcement source told Russia's Interfax news agency the blasts appeared to be the work of Chechen rebels. Police said they were treating the explosions as terrorism.
However, other officials stressed that the attacks could have been carried out by local criminals settling scores.
The blasts happened in residential areas within a few minutes of each other at around 0730 local time (0330 GMT).
Police sources quoted by Itar-Tass said all three devices were loaded with ball bearings and other pieces of metal.
The BBC's Sarah Rainsford in Moscow says there are conflicting reports about exactly what happened, but local police say a 60-year-old man was killed on the spot and two women died later in hospital.
Krasnodar is close to the troubled Caucasus region, and city police were already on high alert.
Investigators were trying to trace the type of explosive device used.
Russian Interior Minister Boris Gryzlov held an emergency long-distance conference with officials in Krasnodar following the blasts, the Interior Ministry's press-service said.
Russia has suffered from ongoing bomb attacks which are usually
blamed on Chechen rebels fighting for independence from Moscow.
Fifty people died earlier this month when a lorry laden with explosives was detonated at a military hospital in Mozdok, in North Ossetia near the border with Chechnya. That attack was also blamed on Chechen separatists.