Element Buffer Object not drawing properly

Hi there, I'm trying to render a simple rectangle using go-gl using an element buffer object. The following is a part of my code:

package main

import (
    "gogame/shaders"
    "runtime"

    "github.com/go-gl/gl/v4.1-core/gl"
    "github.com/go-gl/glfw/v3.2/glfw"

    log "github.com/sirupsen/logrus"
)

var vertices = []float32{
    -0.5, -0.5, 0.0,
    -0.5, 0.5, 0.0,
    0.5, 0.5, 0.0,
    0.5, -0.5, 0.0,
}

var rectangle = []uint{
    0, 1, 2,
    2, 3, 0,
}

func init() {
    runtime.LockOSThread()
}

func main() {
    window := initGLFW()
    defer glfw.Terminate()

    program := initOpenGL()

    var vertexBuffer uint32
    var elementBuffer uint32
    var vertexArray uint32

    gl.GenBuffers(1, &vertexBuffer)
    gl.GenBuffers(1, &elementBuffer)
    gl.GenVertexArrays(1, &vertexArray)

    gl.BindVertexArray(vertexArray)

    gl.BindBuffer(gl.ARRAY_BUFFER, vertexBuffer)
    gl.BufferData(gl.ARRAY_BUFFER, 4*len(vertices), gl.Ptr(vertices), gl.STATIC_DRAW)

    gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, elementBuffer)
    gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, 4*len(rectangle), gl.Ptr(rectangle), gl.STATIC_DRAW)

    gl.VertexAttribPointer(0, 3, gl.FLOAT, false, 0, nil)
    gl.EnableVertexAttribArray(0)

    gl.BindBuffer(gl.ARRAY_BUFFER, 0)
    gl.BindVertexArray(0)

    if err := gl.GetError(); err != 0 {
        log.Error(err)
    }

    for !window.ShouldClose() {

        gl.Clear(gl.COLOR_BUFFER_BIT)
        gl.Clear(gl.DEPTH_BUFFER_BIT)
        gl.UseProgram(program)

        gl.BindVertexArray(vertexArray)
        gl.DrawElements(gl.TRIANGLES, 6, gl.UNSIGNED_INT, gl.PtrOffset(0))
        //gl.DrawArrays(gl.TRIANGLES, 0, 3)

        glfw.PollEvents()
        window.SwapBuffers()

        if err := gl.GetError(); err != 0 {
            log.Error(err)
        }
    }
}

I have a simple vertex and fragment shader set up as well. Running this in wireframe mode gives me something which looks like this:

When in reality it should give me a full rectangle made up of 2 triangles.

If you can get back to me as soon as possible, it would be really helpful.

go-gl / gl

Element Buffer Object not drawing properly #105