OROVILLE, Calif. — Nearly 200,000 people who were ordered to leave their homes out of fear that a spillway could collapse may not be able to return until the barrier at the nation’s tallest dam is repaired, a sheriff said Monday.

Butte County Sheriff Kory Honea did not say how long the fixes could take and offered no timetable for lifting the evacuation order. Officials from the California Department of Water Resources were considering using helicopters to drop loads of rock on the eroded spillway at Lake Oroville, about 150 miles northeast of San Francisco.

Meanwhile, the water level behind the 770-foot-tall Oroville Dam dropped, easing slightly the fears of a catastrophic spillway collapse. But with more rain expected later in the week, time was running short to fix the damage ahead of the storms.

Authorities ordered mass evacuations Sunday for everyone living below the lake out of concern that the spillway could fail and send a 30-foot wall of water roaring downstream.

Asked if the spillway was supposed to handle far more water, the acting head of California’s water agency said he was “not sure anything went wrong” on the damaged spillway.

Bill Croyle said sometimes low-flow water can be high energy and cause more damage than expected. His comments came after officials assured residents for days that the damage was nothing to be concerned about, then ordered everyone to get out in an hour.

The water level in the lake rose significantly in recent weeks after storms dumped rain and snow across California, particularly in the state’s north. The high water forced the use of the dam’s emergency spillway, or overflow, for the first time in its nearly 50-year history.

Suicide bomber strikes Pakistan rally, killing 13 and wounding 58

LAHORE, Pakistan — A suicide bomber struck police escorting a protest rally in the eastern Pakistani city of Lahore on Monday, killing at least 13 people and wounding 58 in an attack claimed by a breakaway Taliban faction.

The blast ripped through the crowd of hundreds of pharmacists, who were protesting new amendments to a law governing drug sales. Six police officers, including a former provincial counterterrorism chief, were among those killed, police said.

Police initially said the attacker was on a motorcycle, but provincial Law Minister Rana Sanaullah later said that closed-circuit footage revealed the bomber was on foot.

A group called Jamaat-ul-Ahrar claimed the attack, saying it was revenge for military operations against Islamic militants along the Afghan border.

Hamas appoints hard-line militant as new leader in Gaza

GAZA CITY, Gaza Strip — Hamas has named a militant commander as its leader in the Gaza Strip, an official media outlet confirmed Monday, placing one of the group’s most hard-line figures in charge of its core power base.

The appointment of Yehiya Sinwar, who was freed by Israel in a 2011 prisoner swap after two decades behind bars, solidifies the takeover of Gaza operations by the armed wing of the group from civilian leaders. The military wing, which controls thousands of fighters, has battled Israel in three wars since Hamas seized Gaza a decade ago.

Sinwar replaces Ismail Haniyeh, who served as the prime minister of Hamas’ government after the 2007 takeover of Gaza and is expected to become Hamas’ supreme leader, replacing Khaled Mashaal, who lives in exile.

Rights Group accuses Syria of

8 chemical attacks in Aleppo

UNITED NATIONS — A human rights group accused the Syrian government on Monday of conducting at least eight chemical attacks using chlorine gas on opposition-controlled areas during the final months in the battle for Aleppo.

Human Rights Watch said in a report released Monday that it used witness interviews and video footage to document government helicopters carrying out the attacks in rebel-held eastern Aleppo that killed at least nine civilians and injured around 200 people.

The attacks took place in areas where government forces were planning to advance, the rights group said.

The Syrian government has denied any chemical attacks. Human Rights Watch said the attacks occurred between Nov. 17 and Dec. 13.

Tour bus flips over on Taiwan highway, killing 32

TAIPEI, Taiwan — A bus carrying Taiwanese tourists on a trip to view cherry blossoms flipped over on an expressway ramp in Taiwan’s capital on Monday, killing 32 people and injuring many others, officials said.

The bus was carrying 44 people when it crashed Monday evening, the Taipei Fire Department said. It said authorities were still trying to determine the cause of the accident.

“It happened on a curve, so the bus flipped, and that could be due to excess speed,” said Tu Bing-cheng, a Taipei official.

Many passengers were trapped under the crushed bus, and rescue personnel used a crane to pry open the vehicle.

The bus belonged to a private company, Tu said. It was taking tourists back from a trip to see cherry blossoms when it crashed, Taipei Deputy Mayor Teng Chia-ji said.

Judge rejects request to halt construction on pipeline

WASHINGTON — A federal judge on Monday rejected a request by two American Indian tribes for an emergency order halting construction of the remaining section of the Dakota Access oil pipeline.

U.S. District Judge James Boasberg, in Washington, D.C., said that as long as the oil isn’t flowing through the pipeline, there is no immediate harm to the Cheyenne River and Standing Rock Sioux tribes. But he said he’d consider the arguments more thoroughly at another hearing on Feb. 27.

The tribes requested the temporary injunction last week after Texas-based Energy Transfer Partners got federal permission to lay pipe under a Missouri River reservoir in North Dakota. That’s the last big section of the $3.8 billion pipeline that needs to be constructed before it carries oil from North Dakota to Illinois.

Venezuelan sanctioned: The Trump administration is slapping sanctions on Venezuela’s new vice president, Tareck El Aissami, and accusing him of playing a major role in international drug trafficking, according to individuals briefed on the U.S. government’s plans. The move freezes El Aissami’s assets in the U.S.

Refugee crisis: More than 1.5 million South Sudanese have become refugees and their humanitarian needs are overwhelming aid efforts during the country’s civil war, according to the United Nations. The civil war began in December 2013, and 3.6 million people have fled their homes or become refugees, the U.N. said.