Although three hours of video from one of Coolidge Park's three surveillance cameras was dark and grainy, Chattanooga police and city officials said the system was doing its job Saturday night when a shooting in the park wounded five people.

"The city has used and will continue to use the cameras to show incidents in the park, investigate situations in multiple areas, and as silent witnesses in a variety of circumstances," said Le Ann Tinker, director of technology with the city's information services department.

"We have suspects in custody," Chattanooga police spokeswoman Rebecca Royval said when asked if the video provided to the media after the event was the same that was provided to the police, and if it was useful in the investigation of a "flash mob" turned sour.

A flash mob is an event sparked by text messaging and posting on social network sites such as Twitter and Facebook and often is planned only hours before it happens.

Ms. Tinker said there are 20 cameras in the Coolidge Park and about 100 throughout the city. The citywide system cost about $400,000 to install, officials said.

The Coolidge Park surveillance cameras are operated by the city and park security, not by police, Officer Royval said. But the cameras have several uses for police, she said, from discouraging crime when suspects spot the cameras to helping police identify suspects who've paid no mind to the surveillance.

Most often, the surveillance videos are used as evidence, she said, but the videos do help with identification - especially when police can show the video to the public and seek tips on a suspect's identity.

Police have charged Anthony Freison, 18, with five counts of attempted first-degree murder, five counts of aggravated assault and one count of felony reckless endangerment in connection with the Saturday shootings.

Taurean Patillo also was charged with five counts of conspiracy to commit first-degree murder and unlawful possession of a weapon. A juvenile also was charged in the incident.

After the shooting incident, Ms. Tinker said, surveillance from all 20 cameras in Coolidge Park was reviewed "with three cameras giving a view of the incident."

Richard Beeland, spokesman for Mayor Ron Littlefield's office, said police have the ability to enhance the video images beyond what the media was given.

Mr. Beeland and Ms. Tinker said the city's yearly maintenance cost for the park cameras is about $4,000, and the city is constantly improving the system.

The cameras, which can be monitored in real time but often are not, are "well worth the cost to purchase and maintain," Ms. Tinker said.

"The cameras have been used to show incidents or lack of an incident during the park's most active hours, which are generally daylight and dusk," she said.

The citywide cameras were approved by the City Council in August 2007. Council members approved by a one-time purchase, installation and networking contract with Motorola that was a not to exceed $660,000. The final amount spent was $420,362, Ms. Tinker said.

The North Shore surveillance includes the 20 cameras in Coolidge Park and five cameras in Renaissance Park, she said.

Officer Royval acknowledged that night video from the system is dark, but daytime video is extremely clear.

"Anytime you have a camera after dark, it's going to be grainy," she said. "You hope that, if there are cameras and people know they're being watched, that they're going to behave. But that's not always the case."

Over the years, a variety of improvements have been made to the cameras, including better focusing and long-distance capabilities. But the cameras never were intended for the kind of conditions experienced Saturday night, she said.

"They were primarily for daylight," she said, adding that other improvements to the cameras for nighttime activities also means trying to find the funds.

"It does require money," she said.

Ms. Tinker also said officials have discussed adding more lights in Coolidge Park, but more lighting means the park could "lose some of its appeal."