Theo Sambuaga, head of a parliamentary commission in charge of security affairs, said that there was evidence the blasts were caused by suicide bombers.
The Ritz and the Marriott are two of the most securely guarded hotels in Jakarta since the 2003 bombing of Marriott hotel by al-Qaeda-linked militants.
Authorities suspect the hand of radical Islamists, Jemaah Islamiyah. Three members of that network were executed last November for their role in the deadly bombing in Bali Island in 2002 that had left 202 people dead.