At least 5,000 people have joined the funeral services for three young Muslim students gunned down in the US state of North Carolina, in what family members said could be a “hate crime”.

The crowd for Thursday’s funeral in the state capital Raleigh was so large it had to be moved from a mosque to a nearby university athletic field.

The gathering was sombre and silent, with only a few children crying in the distance. A large blue plastic prayer mat lay on the field, and some took their own to use. At the service’s end, about a dozen people carried the three coffins to hearses, which headed to an Islamic cemetery outside Raleigh.

Deah Shaddy Barakat, a 23-year-old University of North Carolina dental student; his 21-year-old wife, Yusor Mohammad; and her 19-year-old sister, Razan Mohammad Abu-Salha, were killed at the university town of Chapel Hill on Tuesday allegedly by Craig Stephen Hicks.

The 46-year-old suspect has been charged with three counts of first-degree murder.

Police said a long-running dispute over parking spaces may have prompted the deadly attack.

However, family members of the victims have questioned the official explanation.

Mohammad Abu-Salha, the father of the two women, said at the funeral that he thought the murder had “hate crime written all over it”.

“We don’t want revenge,” he said. “We don’t care about punishment. We want this acknowledged for what it is.”

Gerod King of the Bureau of Alcohol, Tobacco, Firearms and Explosives said that agents were in touch with the US attorney’s office in North Carolina that encompasses Chapel Hill and that investigators had not ruled out a hate crime.

“We understand the concerns about the possibility that this was hate-motivated, and we will exhaust every lead to determine if that is the case,” Chris Blue, Chapel Hill’s police chief, said in an email to reporters.

The cautious wording of the police statement contrasted sharply with the anguished reaction among some American Muslims who viewed the homicides as an outgrowth of anti-Muslim opinions.

Outrage was voiced on social media with the hashtags #MuslimLivesMatter and #CallItTerrorism.

“Based on the brutal nature of this crime … the religious attire of two of the victims, and the rising anti-Muslim rhetoric in American society, we urge state and federal law enforcement authorities to quickly address speculation of a possible bias motive in this case,” Nihad Awad, of the Council on American-Islamic Relations, said in a statement.

Hicks, who appeared briefly in court on Wednesday, is being held without bond. Police said Hicks turned himself in and was cooperating. Al Jazeera