By Jim Forsyth

SAN ANTONIO, Texas (Reuters) – Mandatory evacuations were ordered on Tuesday along the swollen Brazos River in Texas ahead of what could be the worst flooding in more than 100 years after at least six people died.

Forecasters predicted more rain as the Brazos rose to levels not seen in 103 years after heavy rainfall late last week and was expected to crest at about 53 feet on Tuesday, according to emergency officials in Fort Bend County, located southwest of Houston.

Jeff Braun, director of the Fort Bend County emergency management office, said many parts of the county would experience water levels “not seen in our lifetime.”

Dozens of people have been rescued from cars and homes in the past 24 hours, according to the agency’s website.

“The water level is going to stay at the same level for 24 to 36 hours before there will be a slow decrease,” Braun said. “If you flood, you’re going to have the water there for a while.”

The storm system dumped up to 22 inches (56 cm) of rain in just a few hours, killed at least six people last week, according to local authorities.

SECURITY TO STOP LOOTING

In Simonton, Texas, in Fort Bend County, officials provided transportation to help residents leave their homes as well as security to prevent looting.

The American Red Cross opened additional shelters in the Houston area.

Several rivers in southeast and eastern Texas were in “major flood stage.” While relatively rare, forecasters have seen a number of such events in Texas over the past year, said National Weather Service meteorologist Patrick Burke.

A swath of Texas including San Antonio, Austin and Houston has been hardest hit, although other areas in the state have also been affected by flooding, including Dallas-Fort Worth, Burke said.

More than 20 inches of rain have fallen over some parts of southeast Texas during the last month, 8 to 10 inches above normal, Burke said.

An area between the Texas cities of College Station and Houston received 17 inches in one extreme situation late last week, he said.

More rain is forecast this week, which could lead to additional flooding, the weather service said. Moderate and heavy rain will hit western and central Texas, then move east, drenching San Antonio, Austin and Houston on Wednesday and Thursday, Burke said.

“This will certainly prolong the problems they’re having there,” Burke said.

(Additional reporting and writing by Suzannah Gonzales; Editing by Colleen Jenkins and Jeffrey Benkoe)