The city has stepped up efforts to inspect buildings' gas lines in the wake of the East Village building explosions last March, after investigators found unauthorized siphoning of gas likely caused the explosion.

The Times reports that the Buildings Department conducted 343 gas line inspections in 2015, five times more than they conducted in 2014. The department has also boosted its number of inspectors, and overhauled how utility companies like Con Edison handle complaints about "unauthorized gas plumbing," forcing the companies to immediately notify the Buildings Department or the Office of Emergency Management so the issue can be addressed.

Earlier this month, the Manhattan District Attorney's office indicted five people in connection with last March's explosion, which leveled three buildings and killed two people. General contractor Dilber Kukic, building owner Maria Hrynenko, her son and building facilities manager Michael Hrynenko, and two plumbers, Athanasios Ionnidis and Andrew Trombettas, were all charged, with DA Cyrus Vance alleging that the workers installed unapproved gas meters at 121 and 119 Second Avenue and set up an unsafe, leak-prone flexible hose system to channel gas into apartments upstairs.

When ConEd discovered the setup and shut off the gas at 121, the Hrynenkos allegedly began tapping gas lines from 119. Kukic and Michael Hrynenko turned the gas in 121 on when ConEd inspected the building in the early afternoon on March 26th, and that later caused the explosion, according to prosecutors.

Master plumber Trombettas also reportedly has been accused of a slew of safety violations and owes thousands of dollars in unpaid fines—he was fined for installing unsafe flexible gas hoses in one Queens building that housed a day care center. "These code violations aren't merely bits of bureaucracy. They are what, in a large city, with a lot of buildings; those codes are what stand between all of us and future explosions," Mark Peters, Commissioner of Department of Investigations, told ABC 7.

Inspectors have since found illegal gas hookups in buildings all over the city, including at 250 Fourth Avenue in Brooklyn, at 39th Place in Sunnyside, Queens, and at 117 Second Avenue, 46 East 7th Street, and 96 Second Avenue in the East Village, all three of which are near the site of last year's explosion.