GWEN IFILL: The flood disaster that's stricken Texas and Oklahoma claimed more lives and property today. At least 16 people have been killed since Saturday and dozens more are missing.

The latest deluge hit Houston after an all-night downpour. Lightning snaked its way across the night sky and the rain fell and fell and fell, 11 inches in about six hours in Southwest Houston. By morning, parts of the nation's fourth largest city were underwater. Hundreds of cars were stopped in their tracks by rising water, causing all-night backups. In some cases, desperate drivers climbed onto the hoods of their cars, waiting for help.

But even tow trucks got stuck. Houston Mayor Annise Parker declared the city a disaster area after more than 500 water rescues.

MAYOR ANNISE PARKER, Houston: The street flooding from the really torrential downpour last night, we have got cars really littered all over the city. And, as the floodwaters go down, that's one of the things we're doing is to make sure that no one was trapped in those vehicles.

GWEN IFILL: In all, about 2,500 vehicles were abandoned by people seeking higher ground. To the west, 40 people were still missing in the hard-hit vacation area of Wimberley, Texas on the Blanco River. Teams kept looking for Laura McComb and her two children, who were swept away in their vacation home. Her husband, Jonathan, was rescued.

Governor Greg Abbott declared disasters in more than three dozen counties. And, in Washington, President Obama promised federal help.

PRESIDENT BARACK OBAMA: We have FEMA personnel already on the ground. They are coordinating with Texas emergency management authorities. And I will anticipate that there will be some significant requests made to Washington.

GWEN IFILL: Meanwhile, on the Mexican border, the death toll from Monday's tornado in Ciudad Acuna rose to 14 after search teams found the body of a baby who'd been swept from its mother's arms.

So far, there's no estimate of the damage done in Texas and Oklahoma. But the National Weather Service is warning of more rain and thunderstorms this week.

JUDY WOODRUFF: A federal judge's ruling that blocked a presidential order on immigration will stand a while longer. A federal appeals court panel refused today to set aside the ruling. It bars the president from shielding immigrants from deportation. The Justice Department is expected to appeal.

GWEN IFILL: The government of Iraq has formally opened a campaign to retake its key western province, Anbar, from the Islamic State group. ISIS fighters captured the provincial capital, Ramadi, last week, after Iraqi forces abandoned the city.

Today's announcement of a counteroffensive came as Shiite militias said they are now taking the lead in the operation.

AHMED AL-ASSADI, Shiite Militia Spokesman (through interpreter): We can see that the city of Ramadi has been besieged from three sides. There are formations from the Iraqi armed forces stationed shoulder-to-shoulder with the formations of Shiite militia. Thus, the city of Ramadi will be blockaded completely. Then, the Iraqi troops will launch a wide-scale attack to liberate Ramadi.

GWEN IFILL: U.S. officials raised concerns about the Shiite militia's involvement and their use of a sectarian code name that could offend Sunnis. Meanwhile, in Syria, state TV reported airstrikes in the northern province of Raqqa have killed 140 Islamic State militants.

JUDY WOODRUFF: Government-allied fighters in Yemen have scored their first major victory in months over Shiite Houthi rebels. Officials said today the pro-government forces captured Dhale, a city that lies on the road to the Port of Aden.

GWEN IFILL: China said today it will expand the reach of its navy and air force to protect its claims in the South China Sea. That came after — days after a U.S. reconnaissance plane flew over areas where the Chinese are building artificial islands. In Beijing, the Defense Ministry dismissed complaints about China's activities.

YANG YUJUN, Defense Ministry Spokesman, China (through interpreter): There are all kinds of constructions all over China everyday, such as building houses, roads, bridges and so on. From the sovereignty point of view, China's construction in the South China Sea is no different than the constructions in other parts of China.

GWEN IFILL: Meanwhile, Taiwan's president offered a plan aimed at easing the tensions. And Japan announced it will join U.S. and Australian forces in upcoming military exercises, for the first time.

JUDY WOODRUFF: Back in this country, cyber-thieves have broken into an IRS database that holds records of more than 100,000 taxpayers. The agency said today the hackers obtained tax returns and other information. The breach lasted from February through mid-May.

GWEN IFILL: Amtrak will install video cameras in locomotive cabs, starting in the Northeast Corridor. The announcement today follows this month's fatal derailment in Philadelphia. The engineer on that train suffered a head injury and has said he cannot remember what happened. Eight people died in the wreck and 200 were hurt.

JUDY WOODRUFF: President Obama pressed the Senate today to extend Patriot Act provisions that authorize bulk collection of phone records. He said — quote — “This needs to get done.” So far, opponents have blocked Senate action, but Majority Leader Mitch McConnell is calling a Sunday session, ahead of a midnight deadline.

GWEN IFILL: And Wall Street spent the day in a bearish mood over Greece's debt and the surging dollar. The Dow Jones industrial average lost 190 points to close near 18040. The Nasdaq fell 56 points. And the S&P 500 dropped 22.