Customs and Border Protection agents apprehended fewer than 12,500 people who illegally entered the U.S. from Mexico in March, making it the lowest monthly number in 17 years, according to written testimony from Homeland Security Sec. John Kelly.

The number of unaccompanied minors and family units who were taken into custody on land dropped sharply to 18,762 in February, the first full month of President Trump’s administration, which Kelly said was a sign of decreased traffic of illegal immigrants. A total 23,589 illegal immigrants were detained in February including ports of entry near the southern border. It’s unclear whether the 12,500 figure for March includes ports of entry numbers.