A Syrian activist group says three intelligence officers have been killed in the capital Damascus.

The Britain-based Syrian Observatory for Human Rights says the three were killed early Tuesday in the Barzeh neighborhood of the Syrian capital. It gave no further information. The Syrian government has not commented.

The 13-month-old Syria conflict has grown more militarized. Rebels seeking to topple President Bashar Assad have ramped up attacks on military targets and security officers.

The U.N. says more than 9,000 people have been killed since the conflict began, most of them civilians.

The Observatory said 55 people were killed on Monday alone, most of them in a Hama neighborhood following a visit by a U.N. monitoring team.