Dāvids Vīksne, a member of Latvia's national U-18 basketball team, was hurt in the blast, Valdis Voins, the head of Latvia's Basketball Association told LTV.
The family living in the house had been offered municipal help, but they refused as it's a summer domicile.
Rescuers were called to the scene at around 9 p.m., and six people had left the building before the rescuers arrived.
An area of about 200 square meters of the building has collapsed.