An earthquake centered near the impoverished Haitian capital of Port-au-Prince caused the collapse of several buildings and an unknown number of fatalities Tuesday. The quake measured 7.0 on the Richter scale and at least 1.8 million people live within the area where the earthquake had its highest intensity.

President Obama said on Tuesday that his “thoughts and prayers” were with the people of Haiti. “We are closely monitoring the situation and we stand ready to assist the people of Haiti,” Obama said in a statement. The Obama administration said that the State Department, USAID and the U.S. military were working to coordinate an assessment of the situation and any possible assistance.

Huffington Post Impact is working to collect a comprehensive list of links and ways to get involved in relief efforts, detailed below.

The U.S. State Department Operations Center has set up the following number for Americans seeking information about family members in Haiti: 1-888-407-4747