When police entered the basement of a house in Epsom, they found nearly 1,400 marijuana plants, with room to grow up to 4,000 in the basement and apparent plans to expand to the rest of the house.

According to a video available at WMUR.com, the residence on Woodcote Drive was absent any signs of human activity—including furniture, dishes or food—and appeared to be set up solely to grow pot plants.

The basement ceiling was a bank of 1,000-watt lights, nurturing small plants that, when mature, could have yielded up to $5,000 each, for a total street value of $4.7 million, according to WMUR.

The growers had wired a customized ventilation and electrical system that repeatedly blew a nearby transformer. Utility workers traced the short back to the residence, where they discovered that the power had been bypassed. Police dispatched to investigate the theft of services found the plants.

State police Maj. David Kelley described it as one of the most sophisticated growing operations they’ve ever seen in the state. As of press time, they had not yet made any arrests in the case and said their investigation was just beginning.