An explosive device has injured five police officers and two other people in the Colombian capital Bogota in the early hours.
The device, which was packed with shrapnel, went off as a police convoy was driving through the southern neighbourhood of Quiroga.
It is not yet clear who may be behind the attack.
Small-scale explosions are not unusual in the capital, but this device seems more complex than previous ones.
Bogota's police commander, Humberto Guatibonza, said the attack had been aimed at his officers.
"These rats attacked the police as they were going about their duties," he said.
The Colombian police force regularly comes under attack from the main rebel groups, the National Liberation Army and the Revolutionary Armed Forces of Colombia (Farc).
But these attacks occur mainly in rebel strongholds on the border with Venezuela and in rural areas of Cauca province.
They have also diminished since the Farc declared a unilateral ceasefire as part of the peace negotiations they are holding with the Colombian government.
The authorities offered a reward for information leading to the authors of the attack.