Officers charged five adults and two juveniles with distribution of crack cocaine and other offenses in that part of the operation, he said.
In the second phase, undercover officers posing as drug dealers arrested nine people who allegedly bought fake drugs, which is a crime.
One woman was also arrested in connection with sex offenses.
Summers said the authorities conducted the "reverse" operation in order to crack down on buyers and "put some fear in their hearts."
The task force normally concentrates on building cases against big-time drug dealers. But he said it is important to attack open-air drug markets from time to time.
"It's something that we felt we needed to do," he said. "We usually go after the individuals that are causing the violence and making a real living ... (but) we have to try to convince people who are out there buying it and keeping these people in business."
When officials conceived of the operation, they had to spend a great deal of time coordinating it, Summers said.
In addition to the police officers involved, Summers said officials alerted the staff at the Washington County Detention Center.
Also a Washington County District Court bond commissioner worked a special midnight to 8 a.m. shift to process the suspects.
Although he termed the operation successful, Summers said it is extremely time-consuming and expensive.
"That is a significant amount of personnel hours devoted to an operation like this. That's why we can't muster one of these every day," he said. "It was a well-planned, well-executed operation."
Summers said the volume of arrests demonstrates Hagerstown's drug problem.
"If we had had the manpower and time we could have easily doubled that number," he said. "There are a lot of people willing to sell in Hagerstown right now. And unfortunately, there's also a lot of people willing to buy."
Summers said it is too soon to tell what effect, if any, Thursday's operation will have on the city's drug areas. The drug business has been booming this year, though, he said.
Summers said the drug task force has initiated about 220 cases so far in 1997, up from last year's record number of 196. While agents routinely arrest large numbers of suspects when they execute warrants, Summers said an operation like Thursday's is uncommon.
But he said it will not be the last.
"We intend to do a lot more over and over and over again until there's no more left to do," he said.