Police said the explosives detonated after being mishandled, and there are conflicting accounts about the blast.
A source told the AFP news agency that they had uncovered plans for a "major attack" at the property.
Mali has seen sporadic attacks from Islamist militants despite a French military intervention in 2013.
Violence is usually concentrated in the north, but last month five people were killed in an attack on a bar in Bamako.
Friday's blast badly damaged the property. Security and UN officials have surrounded the house.
Investigations are under way. Earlier in the day, an interior ministry spokesman told Reuters "we can't talk of a terrorist act at this point".
Islamists overran Mali's north in 2012, but were driven back by a French-led operation.
An explosion at a house in the Malian capital Bamako has killed a security guard and injured at least two other people, officials say.