Nairobi, Kenya (CNN) -- An explosion in the Kenyan capital left two police officers injured on Friday, authorities said.
The blast occurred after an object was hurled at a police vehicle in the Eastleigh suburb. One of the officers was critically injured, said Eric Kiraithe, the national police spokesman.
Kiraithe said he could not confirm whether it was a grenade explosion. There are no arrests and the motive is unknown.
Eastleigh -- about 20 kilometers from the city center -- is mostly inhabited by Somali refugees.