"The plane has just landed. Depressurisation", Maris Gorodtsov, head of the Latvian civil aviation administration, said.
According to Gorodtsov, "the crew reported problems, in such cases there is a request to the nearest airport, the airport of the intended landing".
"All services were ready to receive the flight", he added.
#Squawk7700 Emergency declared
— Flight Emergency (@FlightEmergency) April 26, 2019
SU2101 from Riga to Moscowhttps://t.co/vbpYqV6JYE
/ @CivMilAirhttps://t.co/CAwb00dVdG pic.twitter.com/szwjn81RvT
The number of passengers on board is still unknown, as is whether there are any injured among them.
The plane, a Sukhoi Superjet 100 (SSJ100) with registration number RA-89041, was conducting flight AFL2101 from Riga to Moscow.
The SSJ100 is a twin-engine plane made by Russia's Sukhoi Civil Aircraft Company.