The unsettling images of emaciated children staring up from hospital beds drew strong reaction from readers this week when The New York Times published “The Tragedy of Saudi Arabia’s War,” an interactive article documenting the catastrophic effects of the civil war in Yemen.

Three years of fighting between Saudi-backed government forces and Houthi rebels have created the world’s worst humanitarian crisis. Yemen, the region’s poorest nation even before the war, now faces potential famine. The United Nations warned this week that half its population may soon rely entirely on humanitarian aid to survive.

Though Saudi-backed forces have used blockades to keep humanitarian aid from reaching areas controlled by the Houthis, some aid groups have still managed to work in country.

Here are some ways people can help.

• Unicef works with local authorities and nongovernmental organizations to provide emergency relief for children, and has operations in every governorate in Yemen. It provides health screenings, vaccines, malnutrition treatment, water and school supplies. • Doctors Without Borders operates in 13 hospitals and health centers in the country. It also provides support to 20 public health programs throughout Yemen, where half of the medical facilities have closed because of the conflict. It operates in areas held by the Houthis. • Save the Children provides education and safe places for children. Up to 75 percent of schools in some areas of Yemen have been destroyed, according to the organization, which trains teachers and creates temporary learning spaces. Save the Children also provides cash and vouchers for food. • The International Rescue Committee provides medical training, supplies and drugs to hospitals. The organization says it has reached more than a quarter million people in Yemen with health, nutrition, water and sanitation services.

Charity Navigator, a nonprofit watchdog group, has highly rated the following smaller aid organizations based on a number of criteria including accountability and transparency: