The Army Corps of Engineers exploded a large section of a Mississippi River levee Monday in a desperate bid to save an Illinois town from rising floodwaters.

The corps said the break in the Birds Point levee would help tiny Cairo, Ill., by diverting up to four feet of water off the river. Just before Monday night’s explosions, river levels at Cairo were at historic highs and creating pressure on the floodwall protecting the town.

The blasts were expected to unleash a muddy torrent into Missouri’s side of the river, flooding empty farm fields and evacuated homes in Mississippi County.

Brief but bright orange flashes could be seen above the river as the explosions went off. The blasts lasted only about two seconds. Darkness kept reporters, who were more than a half-mile off the river, from seeing how fast the water was moving into the farmland.

Engineers carried out the blast after spending hours pumping liquid explosives into the levee. More explosions were planned for overnight and midday Tuesday, though most of the damage was expected to be done by the first blast.

But questions remain about whether breaking open the levee would provide the relief needed, and how much water the blast would divert from the Mississippi River. More rain was forecast to fall on the region Tuesday.

Already, the seemingly endless rain has overwhelmed rivers and strained levees, including the one protecting Cairo, at the confluence of the Ohio and Mississippi rivers.

Flooding concerns also were widespread Monday in western Tennessee, where tributaries were backed up due to heavy rains and the bulging Mississippi River. Streets in suburban Memphis were blocked, and about 175 people filled a church gymnasium to brace for potential record flooding.

The break at Birds Point was expected to do little to ease the flood dangers there, Tennessee officials said.

The Ohio River at Cairo had climbed Monday afternoon to more than 61 feet, a day after eclipsing the 1937 record of 59.5 feet.

The river was expected to crest late Wednesday or early Thursday at 63 feet — just a foot below the level that Cairo’s floodwall is built to hold back — before starting a slow decline by Friday.

The high water has raised concerns about the strain on the levee walls in Cairo and elsewhere. Engineers say sacrificing the levee could reduce the water levels at Cairo by about four feet in less than two days.

The Corps of Engineers had been weighing for days whether to blow open the Birds Point levee, which would inundate 130,000 acres of Missouri farmland. Missouri officials said the incoming water would crush the region’s economy and environment by possibly covering the land under sand and silt and rendering it useless.

Maj. Gen. Michael Walsh — the man ultimately responsible for the decision to go through with the plan — has indicated that if blasting open the Missouri levee does not do the trick, he might also make use of other downstream “floodways.” These basins surrounded by levees can be deliberately blown open to divert floodwaters.

Among those that could be tapped are the 58-year-old Morganza floodway near Morgan City, La., and the Bonnet Carre floodway about 30 miles north of New Orleans.

— Associated Press