Teen surprises hospitalized grandfather ahead of her prom: 'It was like pure happiness'

One teen didn't want to attend her senior prom without sharing the moment with a very special man in her life: her grandfather.

Sianni Tirado told "Good Morning America" that she spent her prom day, April 14, surrounded by family and friends as she got ready for her big night. But one person was missing.

Tirado's 78-year-old grandfather, David, was hospitalized due to complications with his pacemaker. His heart only operates at 15 percent, she said.

When her parents asked Tirado, 18, why she was rushing to get ready, she told them, "I have something planned. Just give me a second."

The plan was to surprise her grandfather at the hospital.

The Saint Cloud High School student trekked to the local hospital accompanied by her boyfriend, Darien Creasy, and her grandmother, Iris.

"My boyfriend Darien walked in first and ... they were just talking. And my grandfather asked, 'Where is Sianni? Is she still getting ready?'" Tirado recalled.

Seconds later, Tirado walked in and her grandfather couldn't control himself.

"I just said, 'Hi papa,' and he just burst into tears," she said. "I had no idea that he was going to react that way...he just started bursting into tears and then I started crying. It was like pure happiness."

The teen shared the sentimental moment on Twitter Monday with the caption, "My grandpa was in the hospital on prom night and was upset he couldn’t see me all dressed up. So I went to him. [When he saw me, he said,] 'Oh mama.'"

Her post quickly went viral, with more than 1.3 million views.

Iris Tirado, David Tirado's wife of 57 years, told "GMA" she was also surprised by her husband's reaction.

"Everybody in the room was crying. Her boyfriend, my husband, everybody," she said. "My granddaughter, I call her my daughter because I raised her since she was small, she's fantastic."

Sianni Tirado said she's glad that she could lift her grandfather's spirits especially in his time of medical need.

"My grandpa is like my right hand man," she gushed.