Thirty horses have died since Dec. 26 at Santa Anita, most recently last weekend, and the storied track in California has become a battleground for activists who want to ban the sport.

The Times interviewed regulators and more than two dozen people who work at Santa Anita and found an array of factors that put horses’ lives at risk.

Here’s what else is happening

Casualties in Afghanistan: Two U.S. soldiers were killed today in what the Taliban called an ambush, bringing to nine the total American military fatalities in the country this year.

New press secretary: Stephanie Grisham, a top aide to Melania Trump, will replace Sarah Huckabee Sanders. She will also fill the vacant role of White House communications director.

E-cigarette ban: San Francisco became the first U.S. city to ban the devices, in an effort to curb what experts have described as a nicotine epidemic among teenagers. The leading e-cigarette manufacturer, Juul, is based in the city.

Change at the N.R.A.: The National Rifle Association has shut down production at NRATV and severed all business with its estranged advertising firm. The move comes after two prominent N.R.A. board members criticized NRATV in an article in The Times in March.

New oil leak estimate: A 14-year-old oil leak in the Gulf of Mexico has been releasing as much as 4,500 gallons a day, according to a federal study. The rig’s owner had said the leak involved only three to four gallons a day.