San Francisco police exchanged fire with an armed carjacking suspect who was in a vehicle that officers pursued through the city early this morning, a police spokesman said.Shortly after 5:30 a.m., officers near Laguna and Geary streets spotted a vehicle that was suspected of being carjacked overnight and tried to pull the vehicle over, police Officer Albie Esparza said.The driver of the vehicle refused to stop, and a pursuit ensued. Officers pursued the vehicle through the Mission District and into the city’s Potrero Hill neighborhood where it went off the roadway in the 700 block of Arkansas Street, Esparza said.The vehicle struck a log on the side of the road and came to a stop. At that point, two men got out of the car, and officers saw one of the suspects had a gun in his hand, according to Esparza.At least one of the men shot at the officers, and one officer returned fire. No one was struck by the gunshots, he said.Both men fled into a nearby park, and a perimeter was established around the area. After a search by officers, with the help of K-9 units, one of the men was found and arrested. His name is not yet being released because of the active investigation into the incident, according to Esparza.A weapon was also recovered in the area, he said.The other suspect is still outstanding and believed to be armed. A description of the man was not immediately available, Esparza said.