"The grenades were thrown, so yes it happened. The police (have) already gone to the residence of Hon. Kyagulanyi and they are piecing up evidence at the scene of crime, and trying to find out what really happened," police spokesman Asan Kasingye, said.
But he dismissed as "absurd" the idea that the attacks were politically motivated.
Talking to local NBS TV, Ssewanyana said he was scared but would not give up the fight against the constitutional change.
"I can't give up and am calling upon all Ugandans not to give up because this is a serious fight. What shows the seriousness is the attacks that they have now started against us ... Attacks involving weapons," he said.
In late September, at least five Ugandan lawmakers received hospital treatment for injuries sustained while being dragged out of the parliament by plain-clothes security guards that opposition MPs said were really soldiers from Museveni's special forces.
Those clashes erupted in the chamber over the motion to end the age limit.