NORTH SIOUX CITY, S.D. (AP) — Half of a collapsed rail bridge connecting South Dakota and Iowa was blasted in a controlled demolition, part of the process to remove the bridge months after it fell into the river, swollen from severe flooding.

The steel bridge over the Big Sioux River connected North Sioux City, South Dakota, with Sioux City, Iowa. It was partially underwater after heavy rains in late June brought record high river crests in the two states, along with Minnesota and Nebraska.

The blast on the South Dakota side of the bridge, owned by BNSF Railway, occurred Monday morning, according to reports from broadcast station KTIV in Sioux City, Iowa. Officials established a perimeter on both sides of the river, closing nearby roads and advising people to stay away.

“At 9 a.m. local time, charges were successfully used to cut the bridge span into sections, allowing it to fall into the river for removal,” Kendall Sloan, BNSF communications director, said in a statement.

“The condition and position of the failed spans made controlled blasting the safest way to remove them,” Sloan added.

Sloan said crews will use a crane to remove the fallen pieces over the next week, and a second controlled blast will target the Iowa side of the bridge, likely in September.

Amy McBeth, public affairs director for BNSF, told KTIV that the controlled demolition needed to happen in two parts because a causeway is needed on both sides to allow the heavy equipment near the river.

The design process for a new bridge is underway and the rebuild is expected to take about nine months.