Story highlights Four insurgents involved in first attack were killed after standoff with security forces

Gunmen targeted a building of the Afghan intelligence agency in second attack

(CNN) At least 20 people were killed and more than 100 were wounded Wednesday in two separate attacks in the Afghan capital, police and hospital officials told CNN.

In the first attack, a car full of explosives detonated around midday near Kabul's 6th district police compound, according to Basir Mojahid, a spokesman for the city's police chief. Most of the injured were civilians.

Two insurgents targeted the police compound, while two others entered the nearby police academy, police said.

After a six-hour standoff with Afghan security forces, all four insurgents were killed, Mojahid said.

In the second attack, two gunmen targeted the Afghan intelligence agency Wednesday afternoon, the police spokesman said. The gunmen were killed before reaching the building, police said.