Kelly, who has 18 goals over his last four games against the Nittany Lions (7-4, 1-1), recorded the first six-goal game for a Terp since Grant Catalino scored six against UMBC in 2011.
Trailing at halftime for the first time all season, the Terps (9-1, 2-0 Big Ten) responded by outscoring Penn State 8-6 in the second half. Maryland came into the game having trailed for just 4:29 the entire season.
Redshirt freshman Logan Wisnauskas had a hat trick, senior Adam DiMillo picked up a career-high five ground balls, Will Snider scored a career-high two goals and Jared Bernhardt added two goals and an assist for the Terps, who host No. 9 Rutgers on Sunday at 7 p.m.
No. 7 Towson 16, Delaware 7: Emily Gillingham and Natalie Sulmonte each finished with three goals to lead the host Tigers (10-2, 2-0 Colonial Athletic Association) to a victory over the Blue Hens (5-8, 0-2).
Johns Hopkins 10, Michigan 8: Mackenzie Heldberg scored five goals to lift the visiting Blue Jays (8-5, 1-3 Big Ten) to a win over the Wolverines (5-9, 1-3).
No. 9 Rutgers 16, No. 18 Michigan 8: Kieran Mullins scored eight goals to lead the host Scarlet Knights (8-3, 1-1 Big Ten) to a win over the Wolverines (7-4, 0-2).
No. 4 James Madison 15, Drexel 2: Kristen Gaudian and Elena Romesburg each scored three goals to lift the Dukes (11-1, 2-0 Colonial Athletic Association) to a win over the visiting Dragons (3-9, 0-2).
No. 9 Northwestern 20, No. 20 Notre Dame 10: Selena Lasota and Sheila Nesselbush each scored five goals to push the Wildcats (11-3) to a win over the Fighting Irish (7-7).
No. 13 Stanford 18, Fresno State 2: Areta Buness scored four goals to lead the host Cardinal (11-3) to a win over the Bulldogs (9-5).
Oregon 18, No. 17 Southern California 11: JoJo Hesketh scored five goals to help the Ducks (8-5, 4-3) upset the visiting Trojans (7-7, 5-4).