Authorities in the Dominican Republic are searching on land, by air and in the water for a University of Pittsburgh student who disappeared last week on spring break in Punta Cana.

Sudiksha Konanki, a 20-year-old United States resident, was last seen on surveillance camera with seven other people entering the beach at the Riu República Hotel in Punta Cana after 4:15 a.m. Thursday, the Dominican National Police said in a statement.

“So far, the authorities, multiple authorities here in the Dominican Republic have searched in the waters. They searched using helicopters and other tools. They also searched in the near bay, bushes, trees. They went multiple times around the same areas,” said her father, Subbarayudu Konanki.

Sudiksha Konanki had gone to Punta Cana for spring break ahead of pre-med studies, he said. “My daughter is a very nice girl,” he said. “She’s ambitious. She wanted to pursue a career in medicine.”

Konanki had arrived Monday in the Caribbean nation with five others, said police, who learned of her disappearance after 8 a.m. Friday through a call from the US Embassy in Santo Domingo.

She had told her friends Wednesday she was heading to a party at the resort, her father said. “She went to the beach on March 6 early morning around 4 a.m. with friends and some other guys they met at the resort,” he said. “After that, her friends came back after some time and my daughter did not come back, did not show up from the beach.”

Around 5:55 a.m. Thursday, surveillance cameras captured five women and one man leaving the beach, while Konanki is believed to have stayed behind with a young man, the local police source told CNN.

Later surveillance video shows the man leaving the beach area at 9:55 a.m., the source said, with no sign of Konanki.

Authorities have interviewed that young man to determine what happened when the two were alone, the source said, and Dominican Police are broadening their investigation to corroborate his preliminary version, the agency said. They also are questioning others last seen with Konanki on Thursday to establish where to focus their maritime search.

Sudiksha Konanki’s friends alerted authorities when she didn’t return to her room, her father said. Her companions reported her missing around 4 p.m. Thursday, with her last sighting some 12 hours earlier, the Riu hotel chain said in a statement.

Konanki’s father wants local authorities “to also investigate other possibilities including whether this is a case of kidnapping or human trafficking,” he told CNN on Sunday from Punta Cana. “We don’t think she would be able to survive for more than three days in the water and I think something else might’ve happened to her.”

The US State Department has in place a Level 2 of 4 travel advisory for the Dominican Republic, advising Americans to use increased caution and not display signs of wealth. “Violent crime, including armed robbery, homicide, and sexual assault, is a concern throughout the Dominican Republic,” the agency said in a June advisory.

Officials in Virginia and India also involved

Konanki was at the resort with five other female students from the University of Pittsburgh, according to the sheriff’s office in Loudoun County, Virginia, where her family lives. The Konanki family, originally from India, has lived in the United States since 2006 and are permanent residents.

The sheriff’s office was contacted Thursday evening about Konanki’s disappearance and has followed up with “federal law enforcement, the US State Department and contacts in the Dominican Republic,” it said.

“The embassy of India in the DR has taken the lead working with our state department and law-enforcement on the ground. Our office is supporting those efforts and continuing to investigate locally,” the sheriff’s office said in a statement to CNN.

The Dominican National Emergency System is coordinating search efforts on the island for Konanki.

“In coordination with the Tourism Police, the Civil Defense, the Dominican Navy, the National Police, and other rescue organizations, four teams of drones equipped with advanced technology have been deployed to conduct a thorough search in the coastal area of Bávaro,” the service said in a statement issued on Sunday.

The Riu hotel chain said staff were helping authorities in their search, its statement said, adding, “We want to express our sincerest empathy towards the family and friends during this very difficult time. The safety and wellbeing of our guests are our highest priority, and we are committed to doing everything possible to assist in this situation.”

The University of Pittsburgh urged anyone with information to contact the Loudoun County Sheriff’s Office.

“University officials are in contact with Sudiksha Konanki’s family as well as authorities in Loudoun County, Virginia, and we have offered our full support in their efforts to find her and bring her home safely,” the university told CNN in a statement.

The Embassy of India was “extending all assistance in coordination with government authorities of the Dominican Republic,” it said on Facebook.

This story has been updated with additional information.